Monster Cookie Bars Recipe
Introduction
Monster Cookie Bars are a deliciously chewy treat packed with oats, peanut butter, chocolate chips, and colorful M&M’s. These bars combine all the best cookie flavors into one easy-to-make dessert that’s perfect for sharing or snacking anytime.

Ingredients
- 1/2 cup (111g) salted butter, softened
- 1/4 cup (62g) peanut butter
- 1 cup (246g) brown sugar
- 1/4 cup (58g) granulated sugar
- 2 eggs
- 2 tsp vanilla extract
- 2 cups (304g) all-purpose flour
- 1 cup (100g) rolled oats
- 1 tsp baking soda
- 1/2 tsp baking powder
- 1/2 tsp salt
- 1 cup (200g) semi sweet chocolate chips
- 3/4 cup (150g) M&M’s
Instructions
- Step 1: Line a 9×9-inch pan with parchment paper and set aside.
- Step 2: Preheat your oven to 350°F (180°C).
- Step 3: In a large bowl, cream together the softened butter, peanut butter, brown sugar, and granulated sugar until smooth and creamy.
- Step 4: Add the eggs and vanilla extract, mixing until fully combined.
- Step 5: Stir in the flour, rolled oats, baking soda, baking powder, and salt until a sticky dough forms.
- Step 6: Fold in the chocolate chips and M&M’s evenly throughout the dough.
- Step 7: Pour the dough into the prepared pan and gently press it down to spread and pack it evenly.
- Step 8: Bake for 25 to 30 minutes, or until the top is golden brown and a toothpick inserted in the center comes out mostly clean.
- Step 9: Allow the cookie bars to cool completely in the pan before lifting out using the parchment paper and cutting into squares.
- Step 10: Enjoy your Monster Cookie Bars fresh or as a sweet treat anytime!
Tips & Variations
- For extra chewiness, substitute half the all-purpose flour with whole wheat flour.
- Try swapping M&M’s with chopped nuts or dried fruit for a different texture and flavor.
- To add a festive touch, use seasonal colored candies instead of regular M&M’s.
- Make sure the butter and peanut butter are softened to make creaming easier and the texture smoother.
Storage
Store Monster Cookie Bars in an airtight container at room temperature for 3 to 4 days. To keep them fresh longer, you can refrigerate them for up to a week. Reheat gently in the microwave for a few seconds if you prefer them warm.
How to Serve

Serve this delicious recipe with your favorite sides.
FAQs
Can I freeze Monster Cookie Bars?
Yes, you can freeze these bars. Wrap individual pieces tightly in plastic wrap and place them in a freezer-safe container. They keep well for up to 3 months. Thaw at room temperature before enjoying.
Can I use crunchy peanut butter instead of smooth?
Yes, crunchy peanut butter can be used and will add a bit of extra texture to the bars. Just make sure to cream it well with the butter and sugars for even mixing.
Print
Monster Cookie Bars Recipe
- Total Time: 40-45 minutes
- Yield: 16 bars 1x
Description
These Monster Cookie Bars are a deliciously chewy and indulgent treat packed with peanut butter, oats, chocolate chips, and colorful M&M’s. Perfect for satisfying your sweet tooth with a delightful combination of textures and flavors in every bite.
Ingredients
Wet Ingredients
- 1/2 cup (111g) salted butter, softened
- 1/4 cup (62g) peanut butter
- 1 cup (246g) brown sugar
- 1/4 cup (58g) granulated sugar
- 2 eggs
- 2 tsp vanilla extract
Dry Ingredients
- 2 cups (304g) all-purpose flour
- 1 cup (100g) rolled oats
- 1 tsp baking soda
- 1/2 tsp baking powder
- 1/2 tsp salt
Add-ins
- 1 cup (200g) semi sweet chocolate chips
- 3/4 cup (150g) M&M’s
Instructions
- Prepare Baking Pan: Line a 9×9 inch pan with parchment paper and set it aside for easy removal of the bars.
- Preheat Oven: Set your oven to 350°F (180°C) to ensure it’s ready for baking.
- Cream Butter and Sugars: In a bowl, cream together the softened butter, peanut butter, brown sugar, and granulated sugar until smooth and creamy, which ensures a light and fluffy texture.
- Add Eggs and Vanilla: Beat in the eggs and vanilla extract until mixture is well combined, adding moisture and flavor.
- Combine Dry Ingredients: Add the all-purpose flour, rolled oats, baking soda, baking powder, and salt to the wet mixture. Mix until a sticky dough forms, incorporating all components evenly.
- Mix in Chocolate Chips and M&M’s: Fold in the semi sweet chocolate chips and M&M’s to distribute them throughout the dough, providing bursts of chocolate and color.
- Transfer to Pan: Pour the dough into the prepared pan and loosely press and pack it down to create an even layer.
- Bake: Place in preheated oven and bake for 25-30 minutes or until the tops turn golden brown and a toothpick inserted comes out mostly clean.
- Cool Completely: Allow the cookie bars to cool in the pan completely to set properly before removing and slicing.
- Serve and Store: Cut into bars, enjoy immediately or store in an airtight container at room temperature for 3-4 days to maintain freshness.
Notes
- Using parchment paper makes it easy to remove the bars from the pan without sticking.
- Do not overbake; the bars will firm up as they cool, so take them out when slightly golden.
- You can substitute M&M’s with other candies or nuts for variation.
- Store bars in an airtight container to keep them chewy and fresh for several days.
- Prep Time: 15 minutes
- Cook Time: 25-30 minutes
- Category: Dessert
- Method: Baking
- Cuisine: American
Keywords: monster cookie bars, peanut butter cookie bars, chocolate chip cookie bars, easy cookie bars, baked cookie bars

