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Chewy M&M Cookie Bars

  • Author: Elise
  • Prep Time: 15 minutes
  • Cook Time: 45 minutes
  • Total Time: 1 hour
  • Yield: 9x13 pan 1x
  • Category: Cookies, Cookie Bars, M&M Bars
  • Method: Bake
  • Cuisine: American


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!


  • 3 cups (420g) all purpose flour, spooned and leveled
  • 1 tablespoon (9g) corn starch
  • 1 teaspoon (5g) baking soda
  • 1/2 teaspoon (4g) salt
  • 1 cup (220g) unsalted butter
  • 1 cup (230g) light brown sugar
  • 1 cup (200g) granulated sugar
  • 1/2 tablespoon vanilla extract
  • 3 large eggs (150g), room temperature
  • 1 cup (180g) chocolate chips (180g)
  • 1/2 cup (100g) mini chocolate chips
  • 1 1/2 cup (270g) M&Ms


  1. Preheat your oven to 325 degrees Fahrenheit. Line a 9×13 baking dish with parchment paper and spray with cooking oil to ensure the bars come out cleanly.
  2. In a medium bowl, whisk properly measured all purpose flour, corn starch, baking soda, and salt together.
  3. In a large bowl with a hand mixer or the bowl of a stand mixer that is fitted with the paddle attachment, mix room temperature butter, light brown sugar, and granulated sugar together until smooth. Mix for about 3-4 minutes until the mixture is lighter and color and slightly fluffy in texture.
  4. Add vanilla extract to the batter before adding the eggs one at a time. Thoroughly mix between adding each egg to make sure the batter is smooth and fully combined. Scrape down the sides and bottom of the bowl as necessary.
  5. Slowly add the dry ingredients to the wet while mixing on low speed. Scrape down the bowl as needed. Do not overmix the batter- just mix until the dry ingredients are incorporated.
  6. Add chocolate chips and M&Ms to the batter and mix until combined. Batter will be very thick.
  7. Transfer the batter to the prepared pan. Spread the batter with the knife to make sure the bars cook evenly. Top the batter with additional chocolate chips and/or M&Ms as desired.
  8. Bake for 35-45 minutes or until the sides of the bars are deep golden brown and the middle is light golden brown. A toothpick inserted into the center should come out mostly clean with some crumbs and batter. The bars will continue to cook as they cool. Allow the bars to cool before slicing.

Keywords: Cookie Bars, Chewy Cookie Bars, Thick Cookie Bars, Holiday Cookie Bars, M&M Bars