Best Chewy Monster Cookie Bars Recipe

If you love baking cookies, then you will absolutely enjoy making cookie bars too. These are perfect when you don’t have time to roll the dough or make batch after batch. Cookie bars are pressed down into a single sheet pan and then baked to sweet perfection.

Using a handful of simple pantry staples, these Chewy Monster Cookie Bars will give you the best flavor of a monster cookie without all the work. They are packed with peanut butter and chocolate without any complicated techniques or fancy ingredients. I’ve learned that the best desserts don’t always mean complicated recipes; sometimes the best desserts are the simplest ones to make!

Jump to:

• What are Monster Cookie Bars?
• Key Takeaways
• Ingredient Notes
• How to Make Monster Cookie Bars
• Pro Tips for Monster Cookie Bars
• Variations and Substitutions
• Frequently Asked Questions
• What to Serve with Monster Cookie Bars
• Storage Tips
• More Dessert Recipes
• Monster Cookie Bars Recipe

What are Monster Cookie Bars?

Monster Cookie Bars are thick, chewy dessert bars that combine the flavors of peanut butter, old-fashioned oats, chocolate chips, and colorful M&M candies. Baked together in a single 9×13 pan. These bars are soft-baked texture that stays moist and delicious for days.

Key Takeaways

• Ready in just about 40 minutes or less.
• Uses simple pantry ingredients like oats, peanut butter, and candy.
• Kid-friendly and perfect for parties, potlucks, or bake sales.
• Great for busy weeknights because there is no rolling of dough required.
• Naturally gluten-free with certified gluten-free oats!

Ingredient Notes

Granulated Sugar: Granulated sugar and brown sugar will be blended to get that slightly crisp edge and flavor.

Brown Sugar: The brown sugar will add the molasses undertones to the flavor of the cookie bars while keeping the center chewy.

Butter: Adds a rich, classic buttery undertone to balance out the strong peanut butter base.

Creamy Peanut Butter: Stick to the standard commercial creamy peanut butter like Jif or Skippy; these stay together better than other brands.

Egg: Acts as the binder to hold the dough together.

Vanilla Extract: Provides an aromatic flavor to the dough.

Baking Soda: Essential for the rise of the cookie bars.

Salt: Helps offset the sweetness of the cookie with just a little bit of salty flavor.

Old-Fashioned Oats: Provides a hearty chew to the cookie bars. If you are making these gluten-free, be sure to use certified gluten-free old-fashioned oats.

M&M Candies: Iconic in monster cookies, just a handful brings color and crunch to these cookie bars.

Chocolate Chips: Paired with the M&Ms to bring about maximum chocolate flavor.

How to Make Monster Cookie Bars

1. Preheat the oven to 350°F (175°C). Grease a 9×13-inch baking dish and set aside. You can also line the baking dish with parchment paper if you’d like to remove the bars for serving.
2. In a large bowl, beat together the granulated sugar, brown sugar, softened butter, and peanut butter until smooth and creamy. Add the egg and vanilla, and mix until well combined.
3. Stir in the baking soda and salt, then mix in the oats until evenly distributed. Fold in the M&M’s and chocolate chips. I like to leave ⅓ of the M&M’s out of the batter and save them to press on top.
4. Press the dough firmly and evenly into the prepared baking dish. Sprinkle on extra M&M’s if you saved them, and press them in firmly into the top.
5. Bake for 22–26 minutes, or until the edges are golden brown and the center is set.
6. Let cool in pan before slicing into bars.

Pro Tips for Monster Cookie Bars

• Press firmly to pack the cookie dough into the baking dish using clean hands or the back of a spatula. This will prevent the bars from falling apart when cutting.
• Cool completely before slicing; as tempting as it will be to dig in, they will harden up some as they cool, which is essential for holding their shape when sliced.
• Do not overbake; they will look slightly soft when done in the oven, but will harden up as they cool.
• Use a few M&Ms to press on top so that the color stays vibrant.

Variations and Substitutions

• Mix it up with a variety of fun add-ins such as flavored chocolate chips, different colors of M&Ms, or seasonal M&Ms.
• Add in crushed pretzels for a salty crunch.
• Use certified gluten-free oats to make these gluten-free.
• Old-fashioned oats will work best, but a mixture of instant oats can be used. If you use instant oats, it will change the texture.

Frequently Asked Questions

What to Serve with Monster Cookie Bars

Chantilly Cream

Mint Chocolate Chip Ice Cream

Vanilla Ice Cream

Cold Glass of Milk

Storage Tips

Room Temperature

Store in an airtight container on the counter for up to 5 days.

Freezer

Freeze individual wrapped slices for up to 3 months in a freezer-safe storage bag. Let them defrost for a few hours at room temperature.

More Dessert Recipes

Baking a crowd-pleasing dessert doesn’t require standing over the oven all afternoon. With these Chewy Monster Cookie Bars, you’ll get all that classic flavor with half the effort.