Monster Cookie Bars

Monster cookie bars are jam packed with layers, textures, and flavors. The chewy oat crust and smooth chocolate are the perfect pair.

These bars are called monster because they are a monster of a cookie! Just huge, and gooey, and so extremely delicious. For more cookie musts try the cookie form of this treat: Monster Cookies, or some other fan favorites: Chocolate Chip Cookie Bars and Giant M&M Cookies.

Monster cookie bars stacked on top of each other

Monster Cookies for a Crowd

These ooey gooey monster cookie are bars are PACKED with chocolatey goodness!

The oat-filled crust is crunchy and the perfect base for all of the flavor layers. The combination of melted chocolate and M&Ms give a great contrast – perfect for the oats and chocolate lover!

They are perfect to fulfill that sweet tooth craving, and because you make a pan full they are a great dessert for crowds.

We love to whip these up when we have visitors, or if we want to deliver a special treat to a special someone.

You will love how easy they are to make, my girls love to make them on their own. They feel so proud when they can make a recipe without help. Enjoy these bars together soon, you won’t regret it!

The oat layer of monster cookie bars in a glass baking dish

Tips for Making Them

PREP. Preheat the oven to 350 degrees F and grease a 9×13 inch baking pan.

ADD. Add the oats, flour, brown sugar, salt, softened butter, and ¼ c peanut butter to a medium size bowl and stir together with a spoon.

MIX & PRESS. Once the ingredients have been combined remove 1 cup and set it aside. Add the remaining mixture from the mixing bowl to the greased baking pan and press.

MELT. Add the condensed milk, chocolate chips and ¼ c of peanut butter to a saucepan and melt over medium-low heat. Stir constantly until the chocolate has melted and all the ingredients have incorporated together.

POUR. Pour the melted chocolate mixture on top of the mixture that was pressed into the baking pan, Use a cooking spatula to spread it evenly.

SPRINKLE. Take the 1 cup of the oat mixture that you set aside earlier and sprinkle it evenly over the top of the chocolate layer.

BAKE & SERVE. Top with M&M’s and bake for 25-27 minutes. Once done allow the cookie bars to cool completely before cutting them.

Variations

For me this recipe is perfect as is, but I know that sometimes it’s fun to be able to change things up so I like to give ideas that I think I may try, or that others would like. Here are some easy variations:

  • Use crunchy peanut butter for added nutty texture.
  • Top with Reese’s pieces for more peanut buttery taste.
  • Sprinkle chocolate or white chocolate chips to the top.
  • Use dark brown sugar for a hint of a carmely flavor. The extra molasses may also give a slightly chewy texture.
  • Add toffee bits.
Monster cookie bar recipe in a glass baking dish

Storage Tips

STORE the bars covered tightly with plastic wrap. They should last at room temperature for 3-4 days.

You can also FREEZE the bars for later. I like to cut them before freezing. I’ll wrap each bar with plastic wrap and store them together in a Ziploc.

They’ll easily last in the freezer for 1-2 months.

A stack of monster cookie bars
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Monster Cookie Bars Recipe

5 from 6 votes
Monster cookie bars are jam packed with layers, textures, and flavors. The chewy oat crust and smooth chocolate are the perfect pair.
Course Dessert
Cuisine American
Prep Time 10 minutes
Cook Time 25 minutes
Total Time 35 minutes
Servings 20
Calories 398 kcal
Author Lil’ Luna

Ingredients

  • 1 ½ c quick oats
  • 1 ½ c flour
  • 1 c brown sugar
  • 1 tsp salt
  • ¾ c butter softened
  • ¼ c peanut butter
  • 14 oz sweetened condensed milk
  • 1 bag milk chocolate chips
  • ¼ c peanut butter
  • 1 c M&M's

Instructions
 

  • Preheat the oven to 350 degrees F and grease a 9×13 inch baking pan.
  • Add the oats, flour, brown sugar, salt, softened butter, and ¼ c peanut butter to a medium size bowl and stir together with a spoon.
  • Once the ingredients have been combined remove 1 cup and set it aside. Add the remaining mixture from the mixing bowl to the greased baking pan and press.
  • Add the condensed milk, chocolate chips and ¼ c of peanut butter to a saucepan and melt over medium-low heat. Stir constantly until the chocolate has melted and all the ingredients have incorporated together.
  • Pour the melted chocolate mixture on top of the mixture that was pressed into the baking pan, Use a cooking spatula to spread it evenly.
  • Take the 1 cup of the oat mixture that you set aside earlier and sprinkle it evenly over the top of the chocolate layer.
  • Top with M&M's and bake for 25-27 minutes. Once done allow the cookie bars to cool completely before cutting them.

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About the Author

Kristyn Merkley

My name is Kristyn and I’m the mom of SIX stinkin’ cute kids and the wife to my smokin’ hot hubby, Lo. My mom’s maiden name is Luna, and I’m one of the many crafty “Lil’ Lunas” in the fam. On this site I like to share all things creative - from recipes to home decor to gifts and home decor ideas. Welcome!

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