If you’re looking for a treat that brings together the comforting flavors of peanut butter, chocolate, and a delightful crunch, Monster Cookie Bars are the perfect choice. These bars are simple to whip up, making them an ideal option for busy days or when you’re craving something sweet. With the wonderful mix of oats, peanut butter, chocolate chips, and mini M&M’s, every bite is a delightful experience.
Recipe Information
Prep Time: 15 minutes
Cook Time: 25 minutes
Total Time: 40 minutes
Servings: 12
Difficulty Level: Easy
Nutrition Information (per serving)
Calories: 250
Protein: 6g
Carbohydrates: 30g
Fat: 12g
Fiber: 2g
Sugar: 15g
Sodium: 150mg
Why Make Monster Cookie Bars
Monster Cookie Bars are not only delicious but also incredibly versatile. The combination of oats and peanut butter gives you a cookie experience that’s both satisfying and slightly healthier than your average dessert. You can customize them with your favorite mix-ins, making them a fun treat for every occasion. Whether you’re packing them in lunchboxes, serving at a party, or just indulging on your own, these bars are sure to please.
How to Make Monster Cookie Bars Step by Step
Ingredients
2 cups old-fashioned oats
1 cup all-purpose flour
1/2 teaspoon baking soda
1/2 cup unsalted butter, softened
1 cup brown sugar
1/2 cup granulated sugar
1 cup creamy peanut butter
2 large eggs
1 teaspoon vanilla extract
1 cup mini M&M’s
1 cup semi-sweet chocolate chips
Directions
Preheat your oven to 350°F (175°C) and line a 9×13-inch baking pan with parchment paper. In a medium bowl, whisk together oats, flour, and baking soda. In a large bowl, beat butter, brown sugar, and granulated sugar until creamy. Add peanut butter, eggs, and vanilla extract to the butter mixture and beat until smooth. Gradually add the dry ingredients into the wet mixture and mix until well combined. Fold in the mini M&M’s and chocolate chips. Spread the dough evenly into the prepared baking pan. Bake for 20–25 minutes or until the edges are golden and the center is just set. Cool completely before cutting into bars.

How to Serve Monster Cookie Bars
Serve your Monster Cookie Bars warm with a scoop of vanilla ice cream for an irresistible dessert. For a balanced snack, pair them with a side of fresh fruit or a simple green salad. They also make a fantastic treat with a glass of cold milk, enhancing the flavors and adding a nostalgic touch.
How to Store Monster Cookie Bars
To keep your Monster Cookie Bars fresh, store them in an airtight container at room temperature for up to a week. For longer storage, you can freeze them. Wrap the bars individually in plastic wrap and place them in a freezer-safe container. When you’re ready to enjoy, let them thaw at room temperature or pop them in the microwave for a few seconds to warm them up.
Expert Tips for Cooking Monster Cookie Bars
- Make sure your ingredients are at room temperature for better mixing.
- For an added crunch, consider mixing in chopped nuts like almonds or walnuts.
- Let the bars cool completely before cutting to prevent them from falling apart.
- You can use almond or sunflower butter for a nut-free version.
- Feel free to swap out the M&M’s for your favorite candy or dried fruit.
Delicious Variations of Monster Cookie Bars
- Add a hint of cinnamon or nutmeg for a warm spice flavor.
- Try incorporating coconut flakes for a tropical twist.
- Switch out the peanut butter for a different nut butter for unique flavor profiles.
Monster Cookie Bars are a delightful treat that’s easy to make, bursting with flavor, and customizable to your liking. Whether you’re sharing with friends or keeping them all to yourself, these bars are sure to be a hit. Give them a try, and savor the deliciousness that comes with every bite.

Monster Cookie Bars
Ingredients
Dry Ingredients
- 2 cups old-fashioned oats
- 1 cup all-purpose flour
- 1/2 teaspoon baking soda
Wet Ingredients
- 1/2 cup unsalted butter, softened
- 1 cup brown sugar
- 1/2 cup granulated sugar
- 1 cup creamy peanut butter
- 2 large eggs
- 1 teaspoon vanilla extract
Mix-ins
- 1 cup mini M&M’s
- 1 cup semi-sweet chocolate chips
Instructions
Preparation
- Preheat your oven to 350°F (175°C) and line a 9×13-inch baking pan with parchment paper.
- In a medium bowl, whisk together oats, flour, and baking soda.
- In a large bowl, beat butter, brown sugar, and granulated sugar until creamy.
- Add peanut butter, eggs, and vanilla extract to the butter mixture and beat until smooth.
- Gradually add the dry ingredients into the wet mixture and mix until well combined.
- Fold in the mini M&M’s and chocolate chips.
- Spread the dough evenly into the prepared baking pan.
Baking
- Bake for 20–25 minutes or until the edges are golden and the center is just set.
- Cool completely before cutting into bars.
