Blueberry French Custard Cake
I love a good Parisian dessert, so when a craving strikes, I put on my apron, play some French music, and make this Blueberry French Custard Cake. There is something so satisfying about whisking hot cream into beaten eggs and baking the most creamy and luscious custard cake in a buttery Biscoff crust. Fresh blueberries, lemon zest, tender custard, lemon mascarpone cream, and blueberry sauce, all in an unforgettable dessert.
I love making delicious cakes, and baking is like therapy for me. The house smells fantastic, and every step of the process fills me with joy. Making homemade recipes is about creating sensorial memories that last a lifetime. I would highly recommend trying the Strawberry Poke Cake, German Chocolate Poke Cake, and Baileys Poke Cake. These are not just cakes, they are moments of bliss and happiness that last even after the last crumb is gone.
Table of contents
This homemade custard cake is perfection. I went ahead and topped it with some lemon mascarpone buttercream and homemade blueberry sauce. The buttercream is ideally suited here; it’s like an additional creamy layer, but with a completely different texture from the custard. Also, it adds another decadent level of texture and refreshing flavor.
Sometimes I skip the buttercream when I want to keep the cake a little lighter. However, I always top it with blueberry sauce! You expect to find this cake at a fancy restaurant or bakery, but oh my, how surprised you will be when it comes out of your kitchen. This is the ideal cake for a Sunday family brunch, or for special occasions, and it’s guaranteed to be a crowd pleaser, transporting everyone’s taste buds to Paris!
Why you will love this recipe
- A decadent dish that is easy to make: You don’t have to fly to Paris to delect yourself with an original French dessert. This cake is impressive and elegant, making it ideal for special occasions and guaranteed to be the center of attention.
- Fresh and wholesome ingredients: When you make it yourself, you know what is in it, which is why I enjoy making so many recipes from scratch. While the custard needs some patience, overall it’s an easy-to-follow recipe that even novice bakers can make.
- Versatile: In my opinion, one of the best reasons to try homemade desserts is that you can customize them to suit your taste. I have attempted to make this custard cake with raspberries, strawberries, blackberries, caramelized apples in brown sugar, and chocolate chips; all versions have turned out excellent.
- Make it in advance: I love hosting dinner parties, but I dislike the chaos and stress on that day; that’s why I choose wisely and make a few things ahead of time. This French cake is ideal to be baked 2 days in advance and then assembled just one day before serving.
What you will need
Custard and crust – I wanted the cake to taste very fresh. The custard itself doesn’t feel heavy, since it’s made with just a little flour, butter, heavy cream, vanilla extract, and a few eggs; it’s very creamy and light. I added some lemon zest for some summery brightness and freshness, and also 2 cups of blueberries. A tart burst of juicy blueberries accompanies every delicious bite of this creamy goodness—similarly, a subtle lemon flavor and a delicious caramelized crumble from the Biscoff crust, enhanced with butter and sugar.
Buttercream layer – I wanted the custard cake to shine, and found different ways to balance its texture and flavors. I added a creamy layer of lemon mascarpone cream on top, made with butter, mascarpone, powdered sugar, and lemon zest.
Blueberry sauce – On top of the creamy mascarpone layer, I have decided to add homemade blueberry sauce made with berries, sugar, vanilla extract, and a simple cornstarch slurry to thicken it.
How to make
Prepare the pot: First, I whisk the eggs, egg yolks, sugar, lemon zest, salt, and flour in a large bowl, then set it aside.
Heating the custard: I heat the heavy cream in a small saucepan on medium heat until it starts to boil. Then, I remove it from the heat and stir in the vanilla extract.
Mixing the custard: Slowly, I pour about one-third of the heavy cream into the egg mixture, whisking it constantly. I DO NOT add all the cream at once, the heat will cook the eggs. After stirring, I slowly add half of the cream left and whisk for 30 seconds before gradually adding the rest of the heavy cream and butter, continuing to whisk.
Cool: I cover the mixture with plastic wrap and let it cool on the counter for 20 minutes before chilling it in the fridge for one hour.
Crust: To make the crust, I first preheat the oven to 350°F. Then, I crush the Biscoff cookies in a food processor until I have three cups of crumbs. Then, I mix the crumbs, butter, and sugar in a medium bowl with a rubber spatula until they are well combined.
Press: Next, I press the crumbs into the bottom and slightly up the sides of a 10-inch springform pan, ensuring it is very compact and tight, so the custard does not leak out. I pre-bake it for seven minutes.
Cook the custard: I arrange blueberries on the bottom of the crust. Then, I pour the chilled custard on top and bake it for 50 minutes, or until it is golden all over. I remove it and put it on a wire rack to cool completely.
Make the blueberry sauce: While the cake is baking, I mix blueberries, sugar, and water in a large saucepan over medium heat. I bring the mixture to a low boil, stirring frequently but carefully to avoid crushing the berries. In a small bowl, I prepare the cornstarch slurry and then add it to the blueberry mixture. I continue to simmer the sauce for about 10 minutes, or until it coats the back of a spoon. Then, I set it aside to cool completely before topping the cake.
Make the mascarpone buttercream: Meanwhile, I put the softened mascarpone and butter in the bowl of an electric stand mixer fitted with the wire attachment and cream for 2 minutes on medium speed until smooth. Then, I add sugar, lemon zest, and salt and beat just until well incorporated. If it is too thick, add cream one tablespoon at a time.
Frost and serve: Once the cake is completely cooled, I frost it with the buttercream and then pour the blueberry sauce on top before serving it.
Expert tip
What to do with extra egg whites
First, egg whites will stay fresh in the fridge for three days in an airtight container or in the freezer for several months. Try freezing them in an ice cube tray and storing them in a freezer bag for easier storage. Then, thaw them out as needed. You can use these for omelets and soups such as egg ribbon soup, Chinese chicken corn soup, or hot and sour soup. They are also great for pavlova or almond cookies.
More tips to consider:
- Do not add all the cream to the egg mixture when making the custard. The heat will cause the eggs to cook and curdle.
- You can use a high-powered blender to grind the cookies if you do not have a food processor.
- You could also put the cookies in a zipper baggie and smash them with a rolling pin or a can of vegetables. But make sure you get them super fine. You do not want your custard to leak.
- Castor sugar is a fine sugar that dissolves better. If you don’t have any, you can make your own by running granulated sugar through a food processor.
Recipe variations and add-ins:
- Other fruit: If you cannot find blueberries, you can substitute them for raspberries, blackberries, or strawberries.
- Different crust: The crust can be changed to a graham cracker or another type of cookie if you prefer. I have tried it with Nilla Wafers, and it was a hit with my family.
- Other frosting: This rich cake would also be good with another kind of frosting instead of mascarpone.
- Lighter topping: For a lighter option, top it with whipped cream. I have my own homemade recipe for whipped cream that you can make.
- Other citrus: Blueberry would also be sensational with orange or lime instead of lemon.
Serving suggestions:
This is a rich and creamy dessert that is ideal after a celebration meal. I recommend serving it chilled and cleaning the knife after each cut. Also, to avoid staining the custard layer with blueberry sauce, I run the knife under cold water before each slice. This blueberry French custard cake also tastes incredible served as a semi-frozen dessert with a drizzle of warm caramel sauce and a dollop of vanilla ice cream.
For a romantic dessert for two, serve this with a bottle of Rosé champagne or sparkling wine. They pair well with blueberries. I suggest serving it after a dinner of blueberry pork chops with mashed sweet potatoes and blueberry margaritas. Another delicious and light dinner that would pair well with these fruity desserts is this peach salmon. Since the dessert is so scrumptious, I like to pair it with refreshing iced tea.
How to store leftovers:
- Refrigerate: Store the custard cake in an airtight container for up to 5 days.
- Freezing: Freezing is not recommended if the cake has been frosted. If the custard cake is unfrosted, wrap it in plastic wrap, then in aluminum foil. Please place it in a freezer-safe Ziplock bag and store it in the freezer for up to one month.
- Thaw: Transfer the cake to the fridge and let it thaw overnight.
Frequently asked questions
They are both thick, sweet, creamy desserts, but custard is much smoother and firmer, with a denser and more gelatinous texture. The eggs in the custard cause the protein to thicken when heated, while pudding is thickened by cornstarch or tapioca and does not necessarily need eggs. There are three kinds of custard: baked, stirred, and frozen. This recipe is made with baked custard, which is particularly rich, creamy, and smooth.
For custard to set, your egg yolks must be cooked to a temperature of just under 212 degrees F, which kills the alpha-amylase enzymes and prevents them from digesting the starches needed for the custard to set. It may look thick at first, but as the leftover enzymes start to break down the starch, your custard will soon become watery. It is best to continue cooking your custard for an additional 2 minutes after bubbles start appearing, stirring constantly. However, to fix this problem, you can reboil your custard to kill those enzymes or add some cornstarch slurry to the custard to make it thicker.
Now that you know what underheated custard can do, you need to know what overheated custard does. When your custard is cooked for too long or at a temperature higher than necessary, the proteins in the egg will coagulate and bind together, resulting in a firm texture. This causes clumps and curdling, which is never good. Once you have too many bonds in your custard, it can be hard to break them up, and you may have to start over with new eggs. It can also break down the protein and cause an eggy flavor that you will not like.
Some say that caster sugar (also known as superfine sugar) is a better choice than granulated sugar in delicate recipes, such as custard, because it dissolves more quickly. It has a softer texture, so it is easier to mix into creamy ingredients. But if you want to make this recipe and you only have granulated sugar, there is no reason to run to the store. Add it to a food processor and pulse for a few seconds. Then, run it through a fine strainer before adding it to your recipe.
More recipes with custard:
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French Custard Cake
Ingredients
Custard Cake Filling:
- 2 cups heavy cream
- 3 1/2 tablespoons butter
- 1 teaspoon vanilla extract
- 3/4 cup all-purpose white flour
- 1 1/4 cups superfine caster sugar or white granulated sugar
- 2 eggs at room temperature
- 2 egg yolks at room temperature
- 1/2 teaspoon salt
- zest of one lemon
- 1 3/4 cups blueberries
- extra butter for the mold
Biscoff Crust:
- 3 cups biscoff crumbs
- 10 tablespoons unsalted butter melted
- 2/3 cup granulated sugar
Blueberry Sauce:
- 6 cups fresh blueberries frozen work too
- 1½ cups water
- 1½ cups sugar
- 6 tablespoons cornstarch mixed with 6 tablespoons cold water
- 2 tablespoons vanilla extract
Mascarpone Lemon Buttercream:
- 1 stick butter softened to room temperature
- 5 oz. mascarpone cheese at room temperature
- 2½ cups powdered sugar
- zest of one lemon
- pinch salt
Instructions
Custard Cake Filling:
- In a large bowl, whisk by hand until well combined with the eggs, egg yolks, flour, sugar, lemon zest, and salt. Set aside.
- In a small saucepan, heat the heavy cream on medium until it begins to boil, then remove it from the heat and stir in the vanilla extract.
- Slowly pour 1/3 of the heavy cream into the egg mixture and whisk constantly. Please ensure you DO NOT pour all the heavy cream at once, since the high temperature will cause the eggs to cook.
- Slowly pour the 1/2 of the remaining heavy cream, whisking until combined. Repeat with the remaining boiled heavy cream.
- Cover the bowl with plastic wrap and let it cool on the counter for 20 minutes. Then, transfer it to the refrigerator for one hour.
Biscoff Crust:
- Cover the bowl with plastic wrap and let it cool on the counter for 20 minutes. Then, transfer it to the refrigerator for one hour.
- In a food processor or blender, grind the Biscoff cookies until you get 3 cups of crumbs.
- Mix the crumbs with melted butter and granulated sugar with a rubber spatula in a medium bowl until combined.
- Press the mixture into the bottom of a 10-inch springform cake pan and slightly up the sides. Make sure it is tight and compact; otherwise, the custard will leak.
- Pre-bake the crust for 7 minutes at 350°F (177°C) before adding the custard filling.
- Note: Chill the crust for 2 hours before using it in your recipe for a no-bake dessert.
- Butter the edges of the spring form pan. Layer the blueberries on the Biscoff crust.
- Remove the custard from the fridge and pour it into the pan. Bake for 50 minutes, until golden brown.
- Remove the cake from the oven and place it on a wire rack to cool completely.
Blueberry Sauce:
- The sauce can be prepared while the cake is baking or several days in advance.
- Combine blueberries, water, and sugar in a large saucepan over medium heat. Stir frequently, but be careful not to crush the berries, and bring to a low boil.
- In a small bowl, mix the cornstarch with cold water until the mixture is well combined.
- Slowly stir the cornstarch into the blueberries, careful not to crush them. Simmer until the homemade blueberry sauce is thick enough to coat the back of a metal spoon, about 10 minutes.
- Remove from heat and gently stir in vanilla.
- If you are preparing the buttercream frosting, be sure to let the sauce cool completely before applying it to the cake.
- Note: This recipe yields a large amount of sauce, so consider saving any leftovers for other dishes or consider reducing the quantity by half.
Mascarpone Lemon Buttercream:
- Place softened butter and mascarpone in the bowl of an electric stand mixer fitted with the wire attachment. Turn the mixer to the medium setting and cream until smooth and combined, 2 – 3 minutes.
- Add sugar, ½ a cup at a time. Add lemon zest and a pinch of salt and whisk until well incorporated.
- If the frosting is too thick, add heavy cream one tablespoon at a time until it has reached the desired consistency.
- Top the cooled cake with the lemon mascarpone buttercream, and pour the cooled blueberry sauce on the frosting.
Notes
What to do with extra egg whites
First, egg whites will stay fresh in the fridge for three days in an airtight container or in the freezer for several months. Try freezing them in an ice cube tray and storing them in a freezer bag for easier storage. Then, thaw them out as needed. You can use these for omelets and soups such as egg ribbon soup, Chinese chicken corn soup, or hot and sour soup. They are also great for pavlova or almond cookies.More tips to consider:
- Do not add all the cream to the egg mixture when making the custard. The heat will cause the eggs to cook and curdle.
- You can use a high-powered blender to grind the cookies if you do not have a food processor.
- You could also put the cookies in a zipper baggie and smash them with a rolling pin or a can of vegetables. But make sure you get them super fine. You do not want your custard to leak.
- Castor sugar is a fine sugar that dissolves better. If you don’t have any, you can make your own by running granulated sugar through a food processor.