Chewy Monster Cookie Bars (One-Bowl!)

These Chewy Monster Cookie Bars will only dirty one bowl, and are scary-delicious! They’re thick, chewy, satisfying, and wonderfully chocolatey.

  • Prep Time: 10 mins
  • Cook Time: 20 mins
  • Total Time: 30 mins

Yield: 20 1x


  • 1/2 cup white sugar
  • 2/3 cups light brown sugar, packed
  • 2 large eggs, room temp
  • 2 tsp ground cinnamon
  • 1/4 tsp table salt
  • 1 tsp pure vanilla extract
  • 1 cup creamy peanut butter
  • 1/3 cup salted butter, softened to room temp
  • 1 1/2 cup semi-sweet chocolate chips
  • 1 tsp baking soda
  • 3 cups quick-cooking oats
  • 2/3 cup M&M’s


  1. Preheat oven to 350F with rack on lower middle position. Lightly grease a 9×13″ glass baking pan; set aside.
  2. In the bowl of a stand mixer fitted with paddle attachment, mix together both sugars and eggs on medium speed, until well combined. Add cinnamon, salt, vanilla, peanut butter, and butter; mix until fully incorporated. Using a wooden spatula, stir in the chocolate chips, baking soda, and oats. Stir to combine well. Scrape dough into prepared pan and lightly/evenly press to fill all corners. Lightly press M&M’s evenly across top of dough.
  3. Bake 20 minutes or just until sides are golden brown. Do not over-bake. Bars will continue to set firmly upon cooling. Cool in pan, on wire rack completely. Cover and chill for ease of cutting. Cut chilled bars into squares and serve.


Baked bars can be wrapped tightly and frozen for 1-2 weeks.

  • Author: Chew Out Loud
  • Category: dessert