Monster Cookie Bars are a one bowl recipe packed with peanut butter, oats and mini m&ms. They're the perfect afternoon snack, dessert or pack a square in the kiddos lunch box. These are a must bake recipe that takes less than 10 minutes to prep and they stay chewy and fresh for days!
I'm always looking for easy, homemade snack ideas and these Monster Bars are one of my kid's and husband's favorites.
I love these cookie bars because they whip up in one bowl with simple pantry ingredients and they taste so yummy. It's like a thick version of a cookie. How could you go wrong with that?
For more fun cookie recipes, try these Coconut Pecan Cookies, White Chocolate Chip Cookies, and Homemade Lemon Curd Cookies.
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Why You'll Love These Cookie Bars:
- The Taste. These bars are chewy with big flavor from the peanut butter and chocolate!
- Easy to Make. Monster Cookie Bars take less than 10 minutes to prep and just 20 minutes to bake.
- Minimal Mess. The recipe is made all in one bowl.
- Great for Snack and Lunch Boxes. The kids can grab a square for snack or dessert. Plus, these are great to pack for school or camp lunches.
Try these Lemon Bars with Graham Cracker Crust and Key Lime Pie Bars too!
Ingredients🍪:
All Purpose Flour: The perfect versatile flour for baking cookies, cakes, muffins and more.
Baking Soda: Helps the cookies rise in the pan.
Old Fashioned Oats: Give the cookie bars some extra texture and they're healthy and high in fiber.
Brown Sugar and White Sugar: I love the combination in cookies because you get the fluffy texture with the granulated sugar and the deep caramel molasses flavors from the brown sugar.
Eggs: Binds the batter together while adding structure and moisture for that nice chewy texture.
Melted Butter: Makes the bars really soft and compact, almost like a brownie texture.
Peanut Butter: Added for taste and pairs really well with the chocolate mini m&ms.
M&Ms: I prefer the mini m&ms for this recipe for their small size.
*You also need an 8x8 pan and parchment paper.
*Full recipe ingredients and quantities can be found in the recipe card below.
Substitution Ideas:
If you can't find mini m&ms, the regular size are fine too.
I highly recommend a peanut butter like Jif or Skippy for this recipe, as sometimes the natural versions don't provide the same texture when baking. I have not tested natural versions for this recipe.
For more kids lunch box ideas, try these DIY Pizza Lunchables, Watermelon Fries and Turkey and Cheese Roll Ups.
How to Make Monster Cookie Bars:
Step 1: Preheat the oven to 350 degrees. Spray a bit of vegetable oil on the bottom of the 8x8 pan and line with parchment paper. Melt the butter in a pan or in the microwave and allow to cool for 10 minutes.
Step 2: In a large bowl, stir flour, oats, brown sugar, granulated sugar, salt, and baking soda until combined.
Step 3: Into the dry ingredient bowl, stir in eggs, vanilla extract, and warm melted butter.
Step 4: Add in the peanut butter and stir to combine. Then, toss in the mini m&ms and stir until mixed well.
Step 5: Plop the cookie dough over the parchment lined pan and use another piece of parchment paper to push it into an even layer in the pan. Make sure to push it into the corners well too. Note: If you don't use the parchment paper, it will be extremely sticky on your hands and hard to flatten into place.
Step 6: Bake for 20 minutes at 350 degrees.
Step 7: Allow the cookie bars to cool for 1 hour before removing from the pan.
Step 8: Once cooled, carefully remove from pan and use a large knife to slice into 16 equal squares. Serve and enjoy! These taste great with a cold glass of milk.
Expert Tips 👨🍳:
- Make sure the butter is cooled to avoid cooking the egg when adding it to the bowl. You want it cooled off, but still warm and pourable.
- The dough is sticky, so using parchment paper on the bottom of the pan will help it from sticking. Also, save a piece to push down the batter into place and work it into the corners. This is a lifesaver and I always use it when making cookie bars and rice krispie treats.
- Leave the parchment paper higher than the batter on at least one of the four sides of the pan for easy removal.
- Don't use a 9x13 dish. This recipe is for an 8x8 pan and cookie times will differ for a smaller or larger sizes.
- Allow the cookie bars to cool for an hour before removing from the pan and slicing into squares or they will crack.
Love Chocolate Chip recipes? Try these Chocolate Chip Mini Muffins, Marshmallow Chocolate Chip Cookies and Sheet Pan Pancakes from Mix.
Recipe FAQs 📋:
Cookie bars are generally thicker in texture with a soft chewy center. They are baked, then cut into squares like brownies, and have a very similar texture to a brownie.
They taste the best if eaten within 3 days of baking.
Slice in bars for easy grabbing and store in a sealed container or gallon sized ziplock bag on the countertop or in the pantry.
More Treats that Kids Will Love:
If you tried this Monster Cookie Bar Recipe or any other recipe on my website, please leave a 🌟 star rating and let me know how it goes in the 📝 comments below. I love hearing from you!
PrintRecipe
Monster Cookie Bars (One Bowl Recipe)
- Total Time: 1 hour, 30 minutes
- Yield: 16 cookie bars 1x
Description
Monster Cookie Bars are a one bowl recipe packed with peanut butter, oats and mini m&ms. They're the perfect afternoon snack, dessert or pack a square in the kiddos lunchbox. These are a must bake recipe that takes less than 10 minutes to prep and they stay chewy and fresh for days!
Ingredients
- 4 tablespoons salted butter
- ⅔ cup all purpose flour
- ⅔ cup old fashioned oats
- 1 teaspoon salt
- ½ teaspoon baking soda
- ½ cup brown sugar, packed
- ½ cup granulated sugar
- 2 large eggs
- 1 teaspoon vanilla extract
- ½ cup Jif Peanut Butter
- ½ cup mini m&ms
- *You also need an 8x8 pan and parchment paper.
Instructions
- Preheat the oven to 350 degrees. Spray a bit of vegetable oil on the bottom of the 8x8 pan and line with parchment paper. Melt the butter in a pan or in the microwave and allow to cool for 10 minutes.
- In a large bowl, stir flour, oats, brown sugar, granulated sugar, salt, and baking soda until combined.
- Into the dry ingredient bowl, stir in eggs, vanilla extract, and warm melted butter.
- Add in the peanut butter and stir to combine. Then, toss in the mini m&ms and stir until mixed well.
- Plop the cookie dough over the parchment lined pan and use another piece of parchment paper to push it into an even layer in the pan. Make sure to push it into the corners well too. Note: If you don't use the parchment paper, it will be extremely sticky on your hands and hard to flatten into place.
- Bake for 20 minutes at 350 degrees.
- Allow the cookie bars to cool for 1 hour before removing from the pan.
- Once cooled, carefully remove from pan and use a large knife to slice into 16 equal squares. Serve and enjoy! These taste great with milk.
Notes
- Make sure the butter is cooled to avoid cooking the egg when adding it to the bowl. You want it cooled off, but still warm and pourable.
- The dough is sticky, so using parchment paper on the bottom of the pan will help it from sticking. Also, save a piece to push down the batter into place and work it into the corners. This is a lifesaver and I always use it when making cookie bars and rice krispie treats.
- Leave the parchment paper higher than the batter on at least one of the four sides of the pan for easy removal.
- Don't use a 9x13 dish. This recipe is for an 8x8 pan and cookie times will differ for a smaller or larger size.
- Allow the cookie bars to cool for an hour before removing from the pan and slicing into squares or they will crack.
- Prep Time: 10 minutes
- Cooling Time: 1 hour
- Cook Time: 20 minutes
- Category: snack
- Method: bake
- Cuisine: American
Robert
These aren’t only for kids! They are seriously so good and I think I prefer them over cookies.
Tara Smithson
Totally agree! I ate so many, HAHA! Thanks so much for the review.