July 4, 2021 1 Hour

Chewy M&M Cookie Bars

Chewy M&M Cookie Bars are chocolate chip cookies baked in bar form. Ooey, gooey, chewy, and filled with chocolate, these bars are irresistible. They are customizable based on occasion or holiday and are the PERFECT impressive treat to bring to any gathering!

What Are Cookie Bars?

Cookie bars are basically cookies baked in bar form. They are a mix between a cookie and a brownie. These are thicker and chewier than a classic blondie though!

You'll make your cookie batter just as normal, but you'll spread all of the dough into a 9x13 inch pan. Then, you'll bake these bars until they are golden brown.

Do not attempt to make this recipe into cookies, as they will not bake properly due to ratio of baking soda, dry ingredients, and wet ingredients. If you're looking for a cookie recipe, Massive Chocolate Chip Pecan Cookies are calling your name!

cookie bars placed in an "S" curve surrounded by crumbs and M&Ms

Ingredients

All purpose flour: Regular, all purpose flour works beautifully in this recipe. It provides structure while still allowing these bars to be oooey and gooey rather than cakey in texture!
Corn starch: Corn starch is one of my favorite ingredients in cookies. It helps them to be soft and tender, and the same goes for cookie bars.
Baking soda: Baking soda is essential for these cookie bars. Its helps them to rise to be tall and also impacts the texture.
Salt: Salt brings out the sweetness and aids the classic chocolate chip cookie flavor we all know and love!
Unsalted butter: Using unsalted butter allows you to adjust the salt in the recipe yourself. If you need to use salted butter, leave out the salt in the recipe. Make sure to use room temperature butter to ensure your bars come out soft and chewy.
Granulated sugar + light brown sugar: These two contribute to structure, moisture, and flavor. The combination aids for the best impact. Make sure to pack your light brown sugar into the measuring cup when measuring!
Vanilla extract: Vanilla extract contributes to the flavor in these bars. Though there is only ½ of a tablespoon, its impact is mighty!
Eggs: Eggs add to the chewy texture in these bars. Make sure to use room temperature eggs. Simply leave them out for 1-2 hours before baking or place them in a bowl of warm water for 10 minutes before using.
Chocolate chips: I use a combination of regular and mini semi sweet chocolate chips. Feel free to use any size and/or flavor you would like!
M&Ms: You'll see patriotic M&Ms in these pictures for the 4th of July, but any color or flavor of M&M will be fabulous.

horizontal line of cookie slices on a piece of wax paper

M&Ms and Chocolate

The best part about these chewy M&M cookie bars is how customizable they are. You can use any color, size, or type of M&Ms you would like. You can use mini M&Ms, dark chocolate M&Ms, peanut M&Ms.... whatever you have or whatever the occasion calls for!

The same goes for the chocolate chips. I prefer to do a combination of mini and regular semi sweet chocolate chips, but you are more than welcome to do white chocolate, chocolate chunks, or any other type or form of baking chocolate!

Baking Cookie Bars

Here are a few of my tips and tricks for perfect chewy M&M cookie bars.

Pan Size: I HIGHLY recommend using a 9x13 inch pan. Using a smaller pan will require a longer baking time and will likely brown the edges and top before the inside is properly cooked. A larger pan will create thinner bars and will require a shorter baking time to ensure that they are not overbaked.
Glass vs. Metal Pan: I bake these bars in a glass pan, but you can use a metal pan. You'll probably need a few less minutes in the oven since metal will trap more heat. Using a metal will likely create crispier edges.
Bake Time: Bake these bars until they are golden brown around the edges and light golden brown towards the center. A toothpick inserted into the center should come out mostly clean... not clean. These bars are meant to be gooey and chewy, and overbaking them will lead to a drier, cakier texture. The bars will continue to cook as they cool.

stack of cookie bars with one in focus displaying the chewy center

FAQ

What is room temperature butter?

Room temperature butter is crucial for best results in this recipe. Room temperature butter is cool and slightly firm to the touch. You should be able to push into the butter without breaking the butter stick. It should not be slimy, greasy, or melty, but it should be soft. Simply leave your butter out 1-2 hours before baking. If you forget, cut your butter into tablespoons. Place the pieces in the microwave for 15 seconds before flipping each piece over and microwaving for 10 seconds. Repeat this process in 5 second increments until your butter reaches the proper consistency.

Can I bake these bars into cookies?

Do not attempt to bake bars into cookies. The ratio of ingredients is suited for these to be baked into bars.

How do I store cookie bars?

Store cookie bars at room temperature for up to 3 days. You'll want to store them covered or in an airtight container to maintain freshness. The bars will lose moisture as they sit. You can freeze these bars. Wrap the bars in cling wrap before placing them in a bag or container for up to 4 months.

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