Easy M&M Cookie Bars

For a sweet treat with crisp edges and soft centers, make these M&M cookie bars! It's so simple - there's no chilling, scooping or rolling of the dough with this recipe. Just press and bake!

Three M&M Cookie Bars stacked on top of each other, and the top one has a bite taken out of it.

Table of Contents

Bar desserts are one of the simplest sweet treats to make, and they're great for summer time!

Cookie bars stand up to the warm weather better than a custard pie or icebox cake. This makes them the perfect solution when you need a delicious dessert for a potluck or picnic.
These M&M cookie bars have the absolute best flavor and texture.

Why You'll Love This Recipe

Super simple, no-fuss recipe. You'll have a dessert with the flavor of M&M drop cookies, but without the fuss of chilling, scooping, or rolling the dough!
Recipe is easy to double for more servings. As written, this recipe yields 16 bars. For a larger batch, use a 9x13-inch dish and double the ingredients.
Freezer-friendly. Make a large batch of dough to bake up later, and/or freeze the baked bar cookies to enjoy up to 3 months later.

Perfect for a simple treat, or if you're looking for something to share with friends for a party or the holidays - these will become a dessert staple once you try them!

Platter of bar cookies with red, green, blue, and yellow candies.

Ingredients

See ingredient substitutions in the next section. ⬇️

flour: This is the base ingredient for any cookie recipe. I prefer unbleached all-purpose flour because it's less processed than bleached flour.
leavener: Baking soda helps the bars rise in the oven. This recipe will not work with baking powder.
cornstarch: Rather than using a third egg yolk, I use cornstarch for additional softness.
salt: Adds flavor, while also balancing the sweet ingredients in the cookie bars.
butter: By using melted butter (and some extra flour), you'll avoid having to haul out the electric mixer.
sugar: You'll need both light brown sugar and white granulated sugar for this recipe. By using more brown sugar than white, the dough has more moisture, which creates super soft cookie bars.
eggs: Eggs add structure, which binds the dough together.
vanilla extract: Pure vanilla extract adds flavor. If you have any homemade vanilla extract, use that!
M&M candies: I use classic plain M&Ms with this bar cookie recipe.

📖 Time-Saving Tip - Testing Baking Soda for Freshness

This simple little test can save you time and money, because if your leavener is expired, whatever you're baking wont rise in the oven! This test works for baking soda and baking powder:

Add about ½ teaspoon of baking soda or powder to a small bowl. Stir in an equal amount of an acidic ingredient, like vinegar or citrus juice.
If the solution doesn't start to bubble immediately, it's time to replace your leavener.

Ingredients in small bowls on a marble counter top: : All-purpose flour, eggs, M&M candies, cornstarch, butter, white sugar, vanilla extract, baking powder, brown sugar, and salt.

Substitutions and Recipe Variations

all-purpose flour: If you'd like to make your M&M cookie bars gluten-free, substitute the AP flour with any cup-for-cup variety of gluten-free all-purpose flour. Two popular brands are Bob's Red Mill and King Arthur Flour.
white granulated sugar: To reduce the calories, you can substitute the sugar with any cup-for-cup variety of granulated sugar substitute. Monkfruit sugar is a good option. Light brown sugar can be used as a substitute, but the flavor of the bars will have a stronger molasses flavor.
unsalted butter: If you need or want to use salted butter, just omit the ½ teaspoon of salt this recipe calls for.

This recipe hasn't been tested with plant-based butter substitutes, but you are welcome to test the recipe with your favorite butter substitute.
eggs: Egg yolks are important for creating moisture and structure. If you need a substitute, check out my post, Egg Substitutes for Baking Guide
vanilla extract: If you need an alcohol-free flavoring, you can use vanilla essence.
M&M chocolates: Really, any variety/flavor of candy-coated chocolate will work. Most people use regular-size plain or mini M&Ms.

Variations

Add chocolate chips. I add semi-sweet chocolate chips to my M&M cookie recipe, and they taste great in the bars as well. You could even use a different flavor, like peanut butter chips, dark chocolate, or white chocolate.
Decorate with frosting! You may want to pipe a border of buttercream frosting around the edges of the cookie bars. Or, for a bit of tangy flavor, you can use cream cheese frosting.
Add some crunch. Stir in ½ cup of chopped walnuts, pecans, or other chopped nuts.
For a larger batch, just double the recipe ingredients, but bake the bar cookies in a 9x13-inch dish instead of an 8-inch square pan.
Use different colors for holiday desserts. Pick out the colors other than green and red for a Christmas dessert (or buy Christmas M&Ms). For a quick and easy Easter dessert, make the cookie bars using the pastel M&M candies.

How to Make M&M Cookie Bars

Flour, baking soda, salt, and cornstarch in a mixing bowl with a whisk.

Combine dry ingredients.

Whisking two eggs, melted butter, white sugar and brown sugar together in a small white bowl.

Whisk wet ingredients in a separate bowl.

Cookie bar dough in a mixing bowl with a silicone stirring spatula.

Combine wet ingredients with dry ingredients.

Bowl of sweet dessert dough combined with M&Ms

Gently fold in M&M candies.

Baked bar dessert in a square metal baking pan.

Spread cookie dough into baking pan.

Freshly baked M&M Cookie Bars in an 8x8 inch pan before slicing.

Sprinkle M&Ms over the unbaked cookie bars. Then ,bake and cool.

Liz's Tips for the Best Bar Cookies

Line the baking dish with parchment paper. Lining the dish and leaving some overhang on the sides makes it easier to remove the baked bars from the pan.
Cool the bars for 1 hour inside the pan. After an hour, use the parchment to lift the dessert out of the pan. Set it onto a cutting board and slice.
Avoid over baking. Check the bars after about 12 minutes of bake time. If you notice they’re browning too much, tent a piece of foil over the pan for the remaining bake time.
To adjust the consistency: Increase the cooking time slightly for firmer cookie bars. For gooey or chewy M&M cookie bars, reduce the cooking time by 3 minutes.

If you like cookies with a fudgy, chewy or gooey consistency, you might also want to make fudgy brownie cookies.

Overhead of baked M&M cookie bars cut into squares.

Storing and Make-Ahead Instructions

Storing: You can store cookie bars at room temperature for up to 5 days. Just be sure to wrap them well, or keep them in an airtight container.

Freezing: In a freezer-safe container, the M&M cookie bars will keep for up to 3 months.

Making the dough ahead of time: You can make the cookie dough ahead, and chill it in the refrigerator for up to 3 days, or freeze it for up to 3 months. Before baking, allow it to come to room temperature.

M&M Cookie Bars Recipe FAQ

Why don’t M&Ms melt in bars and cookies?

The outside coating prevents M&Ms from melting when baked. The inside of the candy does get warm, but it will not melt completely.

How can I keep bar cookies soft?

For the softest cookie bars, avoid over mixing the dough, and be sure to store the baked treats in a tightly sealed container.

An M&M Cookie Bar with a bite taken out of it with a jar of milk in the background.

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