Creamy Potato Gratin with Bechamel Sauce

No holiday spread is complete without my famous creamy potato gratin with Italian Béchamel sauce. Thinly sliced potatoes cook in a creamy, cheesy sauce until golden brown and crisp on the outside, and tender on the inside. I know I can count on this side dish, either for special occasions or comforting homemade dinners.

I love making easy side dishes that work for parties or everyday dinners. Other reader favorites include Bacon Ranch and Cheese Mashed Potatoes, Instant Pot Mashed Sweet Potatoes, and Cheesy Scalloped Potatoes.

This Potato Au Gratin Casserole is my new way to serve delicious potatoes for Christmas dinner or Thanksgiving! It is the ultimate comfort food that is full of flavors, easy to make, and guaranteed to impress. I adapted this indulgent potato side dish from Julia Child’s original recipe. I like making it with either parmesan or mozzarella cheese. Over the years, I found that the parmesan mixture elevates the flavors, resulting in ultra-tender potatoes. However, feel free to use different cheeses or your favorite types. Great alternatives include cheddar, sharp cheddar, or even gruyère.

Why you will love this recipe 

• Simple ingredients: With just potatoes, cheese, cream, and a few basics, I can make a fancy side dish that will impress everyone.
• Easy to prepare: It takes me less than 20 minutes to prepare these cheesy potatoes with just a few easy steps. No special tools or skills are required.
• Better than the box: I know some people prefer to use the stuff in the box because it is “easier,” but once you taste these, you will never go back. The velvety cheese sauce and tender potatoes that actually taste like potatoes will win you over from the first bite.
• Healthier ingredients: I like to make this dish from scratch because I know there are no hidden ingredients or preservatives. I use real cheese, milk, and my own seasonings—no artificial anything.

What you will need

• Produce: I use 5 to 6 medium potatoes, thinly sliced. I prefer Yukon Gold because they have a moderate starch level that helps them hold their shape and a lovely buttery taste. Finely chopped yellow onion distributes a sweet, caramelized flavor that melts smoothly into the sauce.
• Wet ingredients: Unsalted butter adds rich flavor without extra salt, helps bind the sauce, and browns the potatoes. Whole milk provides the right fat and moisture for a creamy, rich sauce without being as heavy as cream. Make sure it is at least 3.25% milkfat, so it doesn’t curdle. Mozzarella has high moisture and melts into a gooey, stretchy texture with a mild flavor that won’t overpower the other ingredients. 
• Ingredients: All-purpose flour has just the right amount of starch to coat the dairy, which helps prevent curdling during cooking. The flour also helps thicken the sauce, no matter what kind of potatoes you use.
• Seasonings: Besides salt and pepper, I also use my own Italian seasoning mix because I can control what goes into it, with no added preservatives or hidden ingredients. 

How to prepare

Preheat the oven: First, I preheat the oven to 375 degrees F and grease a 9×13-inch baking dish with oil.

Sauté the onion: Then, I melt butter in a saucepan over medium heat, add the onion, and cook for about 5 to 6 minutes, or until softened. I stir in the flour, Italian seasoning, salt, and pepper, and cook for 5 minutes, stirring frequently, until it is golden. 

Add the milk: Now, I whisk in 2 cups of milk a little bit at a time, keeping it moving the whole time so it doesn’t scald or separate. Then, I slowly whisk in the other 2 cups of milk until it is smooth. I keep cooking it while whisking until it starts to boil. 

Simmer and add cheese: Immediately, I turn the heat to low and let it simmer gently, stirring occasionally, for about 8 minutes, until it thickens. Then, I remove it from the heat, add salt and pepper to taste, and stir in 1½ cups of shredded mozzarella until it melts. 

Combine: Next, I gently fold the potatoes into the sauce, then spoon it into the baking dish.

Bake until tender: Then, I top it with the remaining mozzarella and bake for 1 hour or until the potatoes are tender.

Rest and serve: I let the creamy gratin potatoes rest for 10 minutes to let the sauce thicken before serving. 

Expert tip

The best potatoes for potato gratin

For this recipe, I want a potato that holds its shape even when sliced thin, but also has enough starch to help thicken the cream sauce. I like Yukon Gold potatoes because they are right in the middle when it comes to starch. They hold their shape and have plenty of starch. They also have a buttery flavor that I love. Russet potatoes are good for thick, creamy sauce, but they sometimes break down too much. Red potatoes, fingerlings, and other waxy potatoes hold their shape well, but you’ll need other ingredients to thicken the sauce. 

More tips to consider:

• Use plenty of Italian seasoning. It is what gives it its flavor.
• Let the milk come to room temperature before using it so it acclimates better.
• Slice the potatoes thin but not too thin. If they are too thin, they will not have any bite. I recommend a mandoline slicer.
• Shred your own cheese for the creamiest sauce. Pre-shredded cheese has plant fibers made from wood pulp to keep the cheese from clumping. But this also prevents it from melting smoothly. 
• Use full-fat milk and cheese to prevent graininess. The fat keeps the sauce from separating and becoming grainy.

Recipe variations and add-ins:

• Add some heat: To make this cheesy potato gratin spicy, add some red pepper flakes or cayenne pepper. But a little goes a long way. 
• Bacon ranch gratin: This dish becomes totally irresistible when you add some crumbled bacon and a bit of my homemade ranch seasoning mix. 
• Crunchy topping: Sprinkle some crushed crackers, corn chips, or potato chips on top before baking for a crunchy topping. 
• Go nuts: Another way to add crunch is with chopped nuts. Walnuts, pecans, or toasted almonds work well. 
• Other cheese: I sometimes use cheddar for a richer, cheesier flavor. Other cheese flavors would be delicious too, such as Parmesan, Gruyère, Swiss, pepper jack, American, Colby, cotija, Gouda, or feta. 

Serving suggestions:

One of my favorite main entrees to serve with these potatoes is pork tenderloin, and this air fryer bacon-wrapped pork tenderloin recipe makes it so easy. The meat is tender and juicy with a brown sugar rub and crispy bacon, and it takes just 30 minutes to cook, so I can have it done before the potatoes are even ready. Another great choice is my Instant Pot country-style ribs. The meat falls right off the bone, and the brown sugar BBQ sauce is rich, thick, and smoky-sweet.

This bacon-wrapped, cream cheese-stuffed chicken pairs perfectly with this creamy potato gratin. The rich cream cheese and mozzarella filling matches the flavors of the béchamel sauce in the potatoes, while the crispy béchamel top and sweet honey glaze add nice contrast. It looks fancy, but it’s not difficult to make in less than an hour. Need more veggies? Add this pineapple cucumber salad to the menu. It has everything from avocados and blueberries to bell peppers and radishes. For dessert, Homemade Snickers cookie bars will satisfy everyone’s sweet tooth. 

How to store leftovers:

• Refrigerate: Save leftovers in a sealed container in the fridge for up to 4 days.   
• Freezing: Freeze leftovers in a freezer bag for up to 3 months, or transfer the mixture to a buttered 9-by-13-inch freezer-to-oven baking dish. Then, cover tightly with aluminum foil. Freeze for up to 3 months.
• Defrost: Thaw leftovers in the fridge overnight. 
• Reheating: Reheat thawed leftovers slowly over medium-low heat until heated through, or bake frozen, covered with foil, at 350°F for up to 30 minutes, or until fully warm.

Frequently asked questions

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