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Gluten Free Monster Cookie Bars

  • Total Time: 50 minutes
  • Yield: 18-24 bars 1x


  • 3 cups old fashioned oats, gluten free if necessary
  • 1 ½ cups quick cooking oats, gluten free if necessary
  • 2 teaspoons baking soda
  • 1 stick unsalted butter, room temperature
  • 1 ½ cups packed light brown sugar
  • ½ cup granulated sugar
  • 1 ½ cups creamy peanut butter
  • 3 large eggs
  • 1 tablespoon pure vanilla extract
  • 1 cup mini Reese’s Pieces
  • 1 cup carob or chocolate chips


  1. Preheat oven to 350 degrees F. Butter a 9 by 13 inch baking pan and line it with parchment. Butter the parchment.
  2. In a large bowl, cream together butter and sugars. Beat in peanut butter, eggs, and vanilla. Mix until light and fluffy. I did this by hand, but a hand or stand mixer will work as well.
  3. Add both kinds of oats and baking soda and stir until well incorporated. Fold in the Reese’s Pieces and chips.
  4. Pour into the prepared pan and spread into an even layer. Bake 30-40 minutes until puffed, golden brown and mostly set in the center. Do not cook until it is all the way set or the bars will be dry. Cool completely in the pan (or don’t 😉 ), cut into bars and serve. Bars may be stored in an airtight container at room temperature for up to 4 days or frozen, individually wrapped in parchment and foil and placed in a zipper bag for up to 3 months. Thaw in the microwave about 1 minute.
  • Prep Time: 10 minutes
  • Cook Time: 40 minutes