If you love the chewy, peanut-buttery goodness of classic monster cookies, but want something even easier to make, these Monster Cookie Bars are about to be your new favorite treat! They’re loaded with peanut butter, oats, chocolate chips, and colorful candy-coated chocolates, giving you that perfect combination of crunchy, chewy, sweet, and salty in every bite.
These bars are thick, gooey, and packed with flavor—perfect for bake sales, lunchbox treats, or just satisfying your sweet tooth. Plus, since they’re baked in one pan, they’re way easier than scooping out individual cookies. Just mix, press, bake, and enjoy!
Why You’ll Love Monster Cookie Bars
Chewy, Gooey, and Loaded with Goodness
Soft in the center, slightly crispy on the edges, and packed with peanut butter, oats, and chocolate.
One-Pan Wonder
No need to scoop out individual cookies—just press the dough into a pan and bake!
Perfect for Any Occasion
Great for parties, potlucks, lunchboxes, or a fun weekend baking project.
Customizable
Swap out candies, add nuts, or use different chocolate chips to make them your own.
Make-Ahead Friendly
These bars store well and taste even better the next day!
Ingredients in Monster Cookie Bars
Each ingredient plays a key role in creating these chewy, peanut-buttery bars:
Butter: Gives the bars their rich, melt-in-your-mouth texture.
Peanut Butter: The classic flavor that makes monster cookies so irresistible.
Brown Sugar & Granulated Sugar: A mix of both sugars adds chewiness and depth of flavor.
Eggs: Helps bind everything together for a perfect texture.
Vanilla Extract: Enhances the flavor and adds warmth.
Oats: Creates that signature chewy texture and adds a bit of heartiness.
All-Purpose Flour: Holds everything together while keeping the bars soft.
Baking Soda: Helps the bars rise slightly for the perfect thickness.
Chocolate Chips: Because everything is better with melty chocolate!
Candy-Coated Chocolates (M&M’s or Similar): Adds crunch, color, and extra chocolate goodness.
(Note: The full ingredients list, including measurements, is provided in the recipe card directly below.)
Instructions
Preheat the Oven
Set your oven to 350°F (175°C) and grease a 9×13-inch baking pan or line it with parchment paper.
Mix the Wet Ingredients
In a large bowl, cream together butter, peanut butter, brown sugar, and granulated sugar until light and fluffy. Beat in eggs and vanilla extract until well combined.
Add the Dry Ingredients
Stir in oats, flour, and baking soda until the dough is fully mixed. Be careful not to overmix!
Fold in the Chocolate
Gently fold in chocolate chips and candy-coated chocolates, reserving some for sprinkling on top.
Press & Bake
Press the dough evenly into the prepared pan and sprinkle the remaining M&M’s and chocolate chips on top. Bake for 20-25 minutes or until golden brown and slightly firm.
Cool & Slice
Let the bars cool in the pan for at least 20 minutes, then slice into squares.
Serve & Enjoy
Enjoy warm for extra gooeyness or let them cool completely for perfect slicing!
How to Serve Monster Cookie Bars
Classic Style
Enjoy them as-is, straight from the pan!
Warm with Ice Cream
Pair with a scoop of vanilla ice cream for the ultimate dessert.
Drizzled with Chocolate or Peanut Butter
For an extra indulgent touch, drizzle with melted chocolate or peanut butter.
With a Glass of Milk
A cold glass of milk is the perfect companion to these chewy bars.
Crumbled Over Yogurt
Turn them into a fun, crunchy topping for your morning yogurt!
Additional Tips
- Use Old-Fashioned Oats: They give the best chewy texture. Avoid quick oats, which can make the bars too soft.
- Don’t Overbake: The bars will continue to set as they cool, so take them out when they’re just golden on the edges.
- Press the Dough Evenly: This ensures uniform baking and consistent texture throughout.
- Switch Up the Candy: Use peanut butter chips, white chocolate chips, or caramel bits for fun variations.
- Store Properly: Keep in an airtight container at room temperature for 5 days or freeze for up to 3 months.
FAQ Section
Q1: Can I make these without peanut butter?
A1: Yes! Swap peanut butter for almond butter or sunflower seed butter for a nut-free option.
Q2: How do I store leftovers?
A2: Keep in an airtight container at room temperature for up to 5 days or in the fridge for a week.
Q3: Can I freeze Monster Cookie Bars?
A3: Absolutely! Wrap them tightly and freeze for up to 3 months. Thaw at room temperature before eating.
Q4: Can I use crunchy peanut butter?
A4: Yes! It adds extra texture and crunch to the bars.
Q5: How do I make them gluten-free?
A5: Use gluten-free oats and a 1:1 gluten-free flour blend to make them gluten-free.
Q6: Can I make these into cookies instead of bars?
A6: Definitely! Scoop the dough into balls and bake for 10-12 minutes for delicious monster cookies.
Q7: What’s the best way to cut these bars cleanly?
A7: Let them cool completely and use a sharp knife or a plastic knife for smooth slices.
Q8: Can I use dark chocolate instead of milk chocolate?
A8: Yes! Dark chocolate adds a deeper, slightly less sweet flavor that pairs well with peanut butter.
Q9: Do I have to chill the dough before baking?
A9: No need! These bars bake perfectly without chilling.
Q10: Can I double the recipe?
A10: Yes! Use a larger pan or bake in two separate 9×13 pans for a big batch.
Final Thoughts
Monster Cookie Bars are the perfect chewy, chocolate-packed treat that everyone will love. Whether you’re baking for a party, meal-prepping desserts for the week, or just need a quick and easy sweet fix, these bars have you covered. Give them a try, and get ready to fall in love with every delicious bite!
Print
Monster Cookie Bars
- Prep Time: 10 minutes
- Cook Time: 25-30 minutes
- Total Time: 0 hours
- Yield: 12–16 bars 1x
- Category: Dessert, Cookies
- Method: Baking
- Cuisine: American
- Diet: Vegetarian
Description
These Monster Cookie Bars are chewy, gooey, and loaded with peanut butter, oats, chocolate chips, and colorful M&Ms! They’re the perfect one-bowl dessert, easy to make, and great for parties, lunchboxes, or an anytime treat.
Ingredients
- 1 cup unsalted butter, melted
- 1 cup brown sugar, packed
- 1/2 cup granulated sugar
- 1 cup creamy peanut butter
- 2 large eggs
- 2 tsp vanilla extract
- 2 cups old-fashioned oats
- 1 1/2 cups all-purpose flour
- 1 tsp baking soda
- 1/2 tsp salt
- 1 cup semi-sweet chocolate chips
- 1 cup M&Ms
- 1/2 cup mini chocolate chips (optional, for extra chocolatey goodness)
Instructions
- Preheat Oven: Preheat your oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper or lightly grease it.
- Mix Wet Ingredients: In a large mixing bowl, whisk together melted butter, brown sugar, granulated sugar, and peanut butter until smooth.
- Add Eggs & Vanilla: Stir in eggs and vanilla extract, mixing until well combined.
- Combine Dry Ingredients: Add oats, flour, baking soda, and salt, stirring until fully incorporated.
- Fold in Add-ins: Gently mix in chocolate chips and M&Ms.
- Spread & Bake: Spread the batter evenly into the prepared pan. Sprinkle extra M&Ms and mini chocolate chips on top for a bakery-style look.
- Bake: Bake for 20-25 minutes, or until the edges are golden brown and the center is set.
- Cool & Slice: Allow to cool completely before slicing into bars.
Notes
- Peanut Butter Swap: Use almond butter or sunflower seed butter for a peanut-free version.
- Chewier Texture: Slightly underbake for extra gooey bars!
- Storage: Store in an airtight container at room temp for up to 5 days or freeze for up to 3 months.
Nutrition
- Serving Size: 1 bar
- Calories: 320 kcal
- Sugar: 22g
- Sodium: 180mg
- Fat: 18g
- Saturated Fat: 7g
- Unsaturated Fat: 9g
- Trans Fat: 0g
- Carbohydrates: 35g
- Fiber: 2g
- Protein: 6g
- Cholesterol: 30mg