Monster Cookie Bars

Indulge in the ultimate sweet treat with these irresistible Monster Cookie Bars! Combining the classic flavors of peanut butter, oats, chocolate chips, and colorful M&M candies, these bars are a delightful twist on the beloved monster cookie recipe. Whether you’re craving a quick snack or need a crowd-pleasing dessert, these bars are sure to hit the spot.


  • ½ cup butter, softened
  • 1 cup brown sugar
  • ½ cup peanut butter
  • 2 eggs
  • 1 teaspoon vanilla extract
  • 1 ¾ cups all-purpose flour
  • 1 teaspoon baking soda
  • 1 ¾ cups quick-cooking oats
  • ¾ cup semi-sweet chocolate chips
  • 1 cup M&M candies


  1. Preparation: Preheat your oven to 350°F (175°C). Grease a 9 x 13-inch baking pan and set it aside for later use.
  2. Creaming: In a large bowl, cream together the softened butter and brown sugar until smooth. Add the peanut butter, eggs, and vanilla extract, and beat until the mixture is well combined.
  3. Dry Ingredients: In a separate bowl, stir together the all-purpose flour and baking soda. Add these dry ingredients to the large bowl with the wet mixture and stir until fully incorporated.
  4. Mix-ins: Fold in the quick-cooking oats, semi-sweet chocolate chips, and M&M candies until they are evenly distributed throughout the dough.
  5. Pressing: Press the cookie dough mixture into the prepared baking pan, ensuring that it’s spread evenly and covers the entire pan.
  6. Additional Toppings: For an extra burst of color and flavor, add additional M&M candies on top of the dough and gently press them in.
  7. Baking: Place the baking pan in the preheated oven and bake for 14 to 16 minutes, or until the edges are slightly browned and a toothpick inserted into the center comes out clean. Be cautious not to overbake.
  8. Cooling: Once baked, remove the cookie bars from the oven and allow them to cool slightly in the pan before slicing. For optimal results, let them cool completely before slicing into bars, although resisting the temptation to dig in right away may be challenging!

Prep Time: 15 minutes
Cooking Time: 14-16 minutes
Total Time: 1 hour 30 minutes
Servings: 12
Calories per serving: (to be calculated)

Serving and Storage Tips:

Serving Tips:

  1. Serve these Monster Cookie Bars warm with a scoop of vanilla ice cream for an indulgent dessert experience.
  2. Pair them with a glass of cold milk for a classic and satisfying treat.
  3. For a special occasion, drizzle melted chocolate or caramel sauce over the cooled bars for added sweetness and flair.
  4. Pack them in lunchboxes or picnic baskets for a convenient on-the-go snack.
  5. Customize the toppings by sprinkling crushed nuts or additional chocolate chips on top before baking for extra texture and flavor.

Storage Tips:

  1. Allow the cookie bars to cool completely before storing them to prevent moisture buildup.
  2. Store the cooled bars in an airtight container at room temperature for up to 3-4 days.
  3. For longer storage, wrap individual bars tightly in plastic wrap and place them in a resealable freezer bag. Freeze for up to 2-3 months.
  4. To thaw frozen cookie bars, transfer them to the refrigerator overnight or let them sit at room temperature for a few hours.
  5. Reheat chilled or frozen bars in the microwave for a few seconds before serving to restore their soft and chewy texture.

By following these serving and storage tips, you can enjoy these delicious Monster Cookie Bars fresh and flavorful every time, whether you’re serving them to guests or savoring them as a personal treat.


  1. Nutty Twist: Incorporate chopped nuts such as pecans or almonds into the cookie dough mixture for added crunch and nutty flavor.
  2. Trail Mix Blend: Replace the M&M candies with a trail mix blend containing raisins, dried cranberries, and nuts for a wholesome twist.
  3. White Chocolate Delight: Substitute the semi-sweet chocolate chips with white chocolate chips for a sweeter and creamier flavor profile.
  4. Coconut Infusion: Mix in shredded coconut to the dough mixture for a tropical twist and delightful texture.
  5. Protein Boost: Add a scoop of your favorite protein powder to the dough for an extra protein punch, perfect for post-workout snacks.
  6. Caramel Swirl: Drizzle caramel sauce over the cookie dough before baking and swirl it in for a decadent caramel flavor.
  7. Peanut Butter Lover’s Dream: Double the amount of peanut butter for an extra-rich and peanutty taste in every bite.
  8. Double Chocolate Indulgence: Fold in additional cocoa powder and dark chocolate chunks into the dough for a double chocolate explosion.
  9. Fruity Fusion: Mix in dried fruit such as cranberries, cherries, or apricots for a burst of fruity sweetness and chewiness.
  10. Spice Infused: Add a pinch of cinnamon or nutmeg to the dough mixture for a warm and cozy flavor twist.
  1. Fruity Burst: Add dried fruit such as cranberries, raisins, or chopped dried apricots to the dough for a burst of fruity sweetness and chewiness.
  2. S’mores Twist: Mix in crushed graham crackers and mini marshmallows to the dough, along with the chocolate chips and M&M candies, for a delightful s’mores-inspired flavor.
  3. Toffee Crunch: Fold in crushed toffee pieces or caramel bits into the dough for a buttery, toffee-infused goodness in every bite.
  4. Pumpkin Spice Delight: Incorporate pumpkin puree and a dash of pumpkin pie spice into the dough for a seasonal fall-inspired treat that’s cozy and comforting.
  5. Trail Mix Medley: Replace the M&M candies with a mix of nuts, seeds, and dried fruit for a wholesome trail mix-inspired flavor profile with added crunch and nutrition.

These variations offer a fun and creative way to customize your Monster Cookie Bars and satisfy a variety of taste preferences!

FAQs :

  1. Can I use natural peanut butter instead of regular peanut butter?
    • Yes, you can use natural peanut butter, but keep in mind that it may alter the texture slightly.
  2. Can I substitute the eggs in this recipe?
    • Yes, you can try using a flax egg (1 tablespoon ground flaxseed mixed with 3 tablespoons water) or mashed banana as an egg substitute.
  3. How should I store leftover cookie bars?
    • Store leftover cookie bars in an airtight container at room temperature or in the refrigerator for optimal freshness.
  4. Can I freeze these cookie bars?
    • Yes, you can freeze these cookie bars for up to 2-3 months. Wrap them tightly in plastic wrap and place them in a freezer-safe container.
  5. Can I use gluten-free flour in this recipe?
    • Yes, you can substitute all-purpose flour with gluten-free flour in the same quantity.
  6. Can I omit the M&M candies from the recipe?
    • Yes, you can omit the M&M candies or replace them with your favorite mix-ins such as chopped dried fruit or additional chocolate chips.
  7. How can I prevent the cookie bars from becoming too dry?
    • Avoid overbaking the cookie bars and ensure that they are stored properly in an airtight container to retain moisture.
  8. Can I reduce the sugar content in this recipe?
    • Yes, you can adjust the amount of sugar to suit your taste preferences. However, keep in mind that it may affect the texture and sweetness of the bars.
  9. Can I use different types of chocolate chips in this recipe?
    • Absolutely! Feel free to experiment with milk chocolate, dark chocolate, or even peanut butter chips for unique flavor variations.
  10. Can I make these cookie bars ahead of time?
    • Yes, you can prepare the cookie dough ahead of time and store it in the refrigerator for up to 24 hours before baking for convenience.

These Monster Cookie Bars are perfect for any occasion, from family gatherings to bake sales. Their chewy texture, delightful flavors, and colorful appearance make them a hit with both kids and adults alike. Whip up a batch today and watch them disappear in no time!