M&M Cookie Bars – 4 Ingredients Only!
You might not believe it until you try it! These M&M cookie bars are so easy to make with just four ingredients in 30 minutes. There are soft, chewy, buttery, and loaded with red and green chocolate M&M’s. I guarantee it will satisfy your sweet tooth and become your go-to recipe over the holidays.
Christmas baking doesn’t have to be overly complicated; it can be enjoyable and fuss-free when you choose delicious, festive recipes that are easy to make. Like these No Bake Oreo Ornaments, Snowman Truffles, or absolutely outstanding Oreo Fudge.
Table of contents
M&M’s Cookie Bars could easily be the best-kept secret in the dessert books. Since I love M&M’s and cookies, it was natural to try to combine them into this decadent concoction. Not surprisingly, they are a perfect match. In addition, the cookies are effortless to make and super versatile. You can easily customize these with different M&M color variations based on season and occasion.
I love making these Christmas cookie bars with the kids, the joy of topping and mixing the cookies with M&M’s, and arranging them in various orders. The cookies have a fantastic texture, with a chewy, dense, and buttery flavor. Ready in about 30 minutes from start to finish, they should definitely be on your must-try list!
Why you will love this recipe
- They are so easy: making these cookie bars is easy; I can have them in the pan and baked in less than 30 minutes.
- I only need four ingredients: Part of what makes them easy is that you probably already have them.
- The kids love to help: We make this one of our family traditions during the holidays, right along with my other holiday cookies.
- No chilling or rolling required: Unlike regular cookies, I can just spread these in the pan and let them bake like brownies.
What you will need
- Cake mix: I use one box of vanilla cake mix.
- Wet ingredients: I add two eggs for binding, structure, and richness, and to achieve a tender crumb. Melted butter creates a chewier texture and helps develop gluten, resulting in a softer, less dry texture. I use unsalted because I don’t like to have extra salt in my cookie bars.
- M&Ms: I use two cups of regular M&Ms, but any kind will work.
How to make
Preheat the oven: First, I preheat the oven to 350 degrees F, spray a 9×9-inch pan with baking spray, and line the bottom with parchment paper, letting it hang over on two sides.
Stir: Next, I stir the cake mix, eggs, and melted butter in a large bowl until well combined.
Mix in: Then, I stir in the M&M’s.
Bake: Then spread it into the prepared pan. After leveling it with a spatula, I place extra M&Ms on top and bake for 25 to 35 minutes, or until it is light golden brown. I want it to be slightly soft in the middle, but not raw. A pick should come out with moist crumbs.
Let it cool: Then, I let the bars cool in the pan for 15 minutes to firm up before removing them using the parchment paper handles.
Slice and serve: Once they are cool enough, I cut them to serve.
Expert tip
Do not overbake the cookie bars
The biggest mistake with these cookie bars is overbaking. Even though it is difficult and goes against everything you’ve been taught, they need to come out of the oven when they are slightly underdone. They will finish firming up as they cool in the pan. Otherwise, they will dry out and crumble because they are made with cake mix. The middle should look slightly moist but not wet, and the pick should come out with a few moist crumbs.
More tips to consider:
- For thinner bars, you can use a 9×13-inch pan, but cut the baking time to 20 minutes.
- I like to place some M&Ms on top too, so that they look extra festive.
- Be sure to let the parchment paper hang over the sides to make it easier to remove them.
- Remove the bars from the oven while they are still a bit underdone so that they will be soft.
- Let them cool in the pan for 15 minutes before removing them, so they firm up.
- Spray your spatula with a bit of grease to keep the batter from sticking.
Recipe variations and add-ins:
- Add chips: To make these even more delicious, I like to add some chocolate chips for chocolate chip M&M cookie bars.
- Go nuts: I also like to add nuts to these tasty treats. My favorites are chopped pecans, but walnuts are good too.
- Different M&Ms: For a different taste, use a distinct flavor of M&M. Peanut butter, dark chocolate, mint, or caramel would all be amazing, but some of the new ones, such as pretzel, fudge brownie, or English toffee, would be worth a try too. You can even add some mini-M&Ms for variety.
- Other candy: Instead of M&M’s, I sometimes use Reese’s Pieces. The kids love these!
- Brownie bars: For extra chocolatey bars, use brownie batter instead of cake batter. Everything else can remain the same, and these cookie bars will wow any chocolate lover!
- Different flavor cake: As a matter of fact, make the cookie bars any flavor you want by using any cake flavor like red velvet, confetti, coconut, strawberry, or lemon.
- Caramel topping: Sometimes, I like to make these cookie bars even more decadent and luscious by adding some of my rich caramel sauce on top. Then I put it in the fridge for about an hour to set before serving.
Serving suggestions:
When I serve these to the kids, it is with a glass of ice-cold milk or a mug of hot chocolate. My homemade hot chocolate tastes 100x better than any store-bought stuff, and it is so easy to make. The kids actually like dipping their cookie bars into it. For my adult visitors who want something more substantial to go with their cookie bars, I make them some grown-up Bailey’s s’mores milkshakes. With chocolate ice cream, Bailey’s, vodka, chocolate syrup, and marshmallow fluff, this is a dessert cocktail that everyone loves.
These cookie bars also pair well with my other M&M treats, such as these Christmas sugar cookies or rosette cookies, which are simple to make and a delight to show off. The kids love to help me make them, too. They only require four ingredients and 20 minutes! My Christmas light cupcakes are also adorable and fun to make. Since I make them from a box cake mix, they only take about 30 minutes! Easy peasy!
How to store leftovers:
- Refrigerate: Leftovers will stay fresh on the counter in a sealed container for a week or in the fridge for two weeks.
- Freezing: If I wrap them in plastic and put them in freezer bags, I can save them for several months.
- Defrost: For the best flavor, I thaw them overnight before serving.
Frequently asked questions
They were probably overbaked. This is one of the most common mistakes. Baking them too long will make the dough too firm. It may also be from stirring it too much. That causes too much gluten. Only stir until the ingredients are combined. Once the dry ingredients are wet, that is enough stirring. Then, fold in the M&Ms gently with a spatula.
Absolutely, make the dough and press it into the pan, cover it well, and it will stay fresh in the fridge for up to three days. Or roll it into a disc and wrap it in plastic, put it in a freezer bag, and it can stay frozen for 60 to 90 days. If it is chilled in the pan, let it sit at room temperature for an hour before baking to ensure even cooking. For frozen cookie dough, let it thaw overnight, then press it into a pan and bake it once it comes to room temperature.
Too much butter is likely the culprit since it is the only wet ingredient. Be sure to add the right amount carefully. If the batter is too runny before cooking, add a bit of flour or cornstarch one tablespoon at a time. This may also happen if it was not cooked long enough. I know that I say it is important not to cook it too long, but it has to be cooked long enough to set. The middle should be soft but not wet, and the pick should come out with just a few moist crumbs. It should not be doughy.
It is always fun to add more tasty treats like nuts, chocolate chips, or marshmallows, but do not add so much that the dough cannot stay together. If there are too many bulky ingredients, the cookies lack enough structure to hold them together. For those add-ins like chocolate chips and nuts, just cut down on the M&Ms by ½ cup. Better yet, use mini-M&Ms so they take up less space.
More festive Christmas recipes:
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M&M Cookie Bars
Ingredients
- 1 box 15.25oz vanilla cake mix
- 2 large eggs
- 1/2 cup (1 stick) unsalted butter melted
- 2 cups M&M’s red and green
Instructions
- Preheat the oven to 350 degrees F. Spray a 9×9-inch pan with nonstick spray. Line the bottom with parchment paper, allowing it to hang over two sides for easy removal of the cookie bars.
- In a large bowl, stir the first three ingredients together until well combined. Add M&M's and stir until well combined.
- Spread and pat the cookie dough in the pan. Level the top with a spatula.
- Bake for approximately 25 to 35 minutes, or until golden brown. A toothpick inserted into the center should come out clean or with only a few crumbs, not raw batter.
- Allow the cookie bars to cool before cutting them, as this will help them firm up.
- Using the parchment paper handles, lift the cookie from the pan and cut into bars.
Video
Notes
Do not overbake the cookie bars
The biggest mistake with these cookie bars is overbaking. Even though it is difficult and goes against everything you’ve been taught, they need to come out of the oven when they are slightly underdone. They will finish firming up as they cool in the pan. Otherwise, they will dry out and crumble because they are made with cake mix. The middle should look slightly moist but not wet, and the pick should come out with a few moist crumbs.More tips to consider:
- I like to place some M&Ms on top too, so that they look extra festive.
- Be sure to let the parchment paper hang over the sides so it’s easier to remove.
- Remove the bars from the oven while they are still a bit underdone so that they will be soft.
- Let them cool in the pan for 15 minutes before removing them, so they firm up.
- Spray your spatula with a bit of grease to keep the batter from sticking.