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Monster Cookie Bars Recipe

5 Stars 4 Stars 3 Stars 2 Stars 1 Star 3.9 from 2 reviews
  • Author: Sue
  • Prep Time: 15 minutes
  • Cook Time: 30 minutes
  • Total Time: 45 minutes
  • Yield: 24 servings
  • Category: Dessert
  • Method: Baking
  • Cuisine: American

Description

Deliciously chewy Monster Cookie Bars loaded with oats, peanut butter, semi-sweet chocolate chips, and colorful M&M’s, baked to golden perfection and topped with a sprinkle of flaky sea salt for an irresistible sweet and salty treat.


Ingredients

Dry Ingredients

  • 2 cups all-purpose flour, (spooned and leveled)
  • 2 cups old fashioned oats
  • 1 teaspoon baking soda
  • 1 teaspoon sea salt

Wet Ingredients

  • 1 cup unsalted butter, (at room temperature)
  • 1 cup creamy peanut butter
  • 1 1/2 cups packed light brown sugar
  • 1/2 cup granulated sugar
  • 2 large eggs
  • 1 tablespoon vanilla extract

Add-Ins

  • 1 1/4 cups semi-sweet chocolate chips
  • 1 1/2 cups M&M’s, (divided)
  • Flaky sea salt, (for sprinkling on bars)


Instructions

  1. Preheat Oven: Preheat your oven to 350 degrees F (175 degrees C) and generously grease a 9x13-inch baking pan with nonstick cooking spray to prevent sticking.
  2. Mix Dry Ingredients: In a large mixing bowl, whisk together the flour, old fashioned oats, baking soda, and sea salt. Set this mixture aside.
  3. Cream Wet Ingredients: Using a stand mixer, beat the room temperature unsalted butter, creamy peanut butter, light brown sugar, and granulated sugar together until the mixture is smooth and creamy, about 2 minutes. Scrape down the bowl sides if needed.
  4. Add Eggs & Vanilla: Incorporate the eggs and vanilla extract into the creamed butter and sugar mixture, mixing just until combined.
  5. Combine Wet and Dry: Gradually add the dry ingredients to the wet ingredients and mix until just combined. Avoid overmixing to keep the bars tender.
  6. Stir in Chocolate & M&M’s: Fold in the semi-sweet chocolate chips and 1 cup of M&M’s evenly throughout the batter.
  7. Spread Batter & Add Topping: Use a spatula to spread the cookie batter evenly into the prepared 9x13-inch pan. Sprinkle the remaining 1/2 cup of M&M’s over the top for a colorful finish.
  8. Bake: Bake the bars for 25-35 minutes until the edges turn lightly golden and the center is set but still soft. Avoid overbaking to maintain chewiness.
  9. Add Finishing Touch: Remove the baking pan from the oven and immediately sprinkle flaky sea salt over the warm bars to enhance the flavor contrast.
  10. Cool and Serve: Allow the bars to cool completely in the pan before cutting into 24 squares. Serve and enjoy your monster cookie bars!

Notes

  • For best texture, do not overmix the dough once the dry ingredients are added.
  • Keep an eye on the baking time as ovens can vary; bars should be set but still soft in the center.
  • The flaky sea salt on top adds a lovely balance to the sweet chocolate and peanut butter flavors.
  • Store leftover bars in an airtight container at room temperature for up to 5 days.
  • You can substitute M&M’s with other colorful candy-coated chocolates or chopped nuts if preferred.