Monster Cookie Bars are a peanut butter oatmeal cookie bar loaded with m&m's, chocolate chips and an extra layer of peanut butter drizzled through the middle. They're so chewy and bursting with flavor!
These chewy monster cookie bars are thick and chewy and loaded with so much peanut butter and chocolate flavor. And they're so easy to make since they're in a bar form.
For more cookie bars you should try my chewy snickerdoodle cookie bars, my oatmeal carmelita bars, or my s'more cookie bars.
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Why You Will Love These Bars
- Easy to Make: These are even easier to make than actual cookies because you don't have to scoop dough.
- Chewy & Thick: The texture of these bars is so thick and chewy!
- Cute for Holidays: I always love a recipe that you can sub in holiday m&m's for.
Ingredient Notes
Full ingredient measurements and instructions can be found in the recipe card below.
- Peanut Butter: I always suggest using a non-natural peanut butter for baking such as Skippy or Jif.
- Brown Sugar: I love using dark brown sugar for a richer taste, but light works great too!
- Oats: I used old-fashioned, not quick oats
- M&M's: I like using mini so they disperse easier, but regular size is great too.
Recipe Instructions
Here is how to make these bars. You will need a mixing bowl and an 8x8 baking pan.
Step 1: Preheat the oven to 350 F. Grease an 8x8 pan with cooking spray, or line with parchment.
Step 2: In a large mixing bowl fitted with the paddle attachment, cream together butter, ¼ cup of peanut butter and brown sugar until light and fluffy. Add egg and vanilla and mix in.
Step 3: Add the salt, baking soda, flour and oats, mixing until combined. Fold in ½ cup of mini m&m's.
Step 4: Press half the dough onto the bottom of the 8x8 pan. Bake for 10 minutes. You will save the remaining half of the dough for topping.
Step 5: Warm a ½ cup of peanut butter in a microwaveable safe bowl. Top the warm, cooked bottom layer of the bars with both chocolate chips and then drizzle with peanut butter.
Step 6: Place dollops of remaining dough on top, don’t worry about it spreading evenly over the top. Sprinkle extra m&m's on top. Bake an additional 16-18 minutes. Remove from oven and sprinkle with flaked salt. Allow to cool before cutting.
Expert Baking Tips
- I prefer to make these at least a few hours ahead of time so that they can firm up before cutting into.
- You can double this recipe and bake it in a 9x13 pan instead. When doing so add 2-3 minutes to each part of the baking.
- Don't stress about measuring out "half" of the dough for the bottom layer. Just make sure you have a thin layer that covers the bottom, and save the rest of the dough for layering on top.
- You could also bake these in a round cake pan and serve as wedges with ice cream.
FAQ
Yes, these bars will work great subbed with a 1:1 gluten free flour.
Yes, allowing them to cool will let them finish baking so they are the perfect consistency in the middle.
If you wanted to make cookies, I'd use my monster cookie recipe instead.
Storing & Freezing
Monster cookie bars can be stored at room temperature for 3-4 days. Place in a ziplock bag or store in an airtight container. Do not store the bars in the fridge, it will dry them out.
These bars freeze great. You can store them individually in little bags to take and go, or freeze them all together in one airtight container.
Other Popular Recipes to Try
For more yummy treats follow me on instagram @thesaltedsweets. And be sure to tag me and comment if you make them and love them as much as I do!
Monster Cookie Bars
Ingredients
- ¾ cup butter
- ¼ cup creamy peanut butter
- ¾ cup brown sugar light is fine too
- 1 large egg
- 1 tablespoon vanilla
- ½ teaspoon salt
- ½ teaspoon baking soda
- 1 cup all-purpose flour
- 1 cup old fashioned oats
- ½ cup mini m&m's plus more for topping
- ½ cup semi sweet chocolate chips
- ½ cup peanut butter for drizzling
- flaked sea salt
Instructions
- Preheat the oven to 350 F. Grease a 8x8 pan with cooking spray, or line with parchment.
- In a large mixing bowl fitted with the paddle attachment, cream together butter, ¼ cup of peanut butter and brown sugar until light and fluffy. Add egg and vanilla and mix in.
- Add the salt, baking soda, flour and oats, mixing until combined. Fold in ½ cup of mini m&m's.
- Press half the dough onto the bottom of the 8x8 pan. Bake for 10 minutes. You will save the remaining half of the dough for topping.
- Warm a ½ cup of peanut butter in a microwaveable safe bowl.
- Top the warm, cooked bottom layer of the bars with both chocolate chips and then drizzle with peanut butter.
- Place dollops of remaining dough on top, don’t worry about it spreading evenly over the top. Sprinkle extra m&m's on top. Bake an additional 16-18 minutes. Remove from oven and sprinkle with flaked salt. Allow to cool before cutting.
Michele Mechlin
Made these two days ago and they were DEVOURED by my kids and husband. So, so good. And very filling with the peanut butter and oats. Thank you!
brooke
Yay!!! So happy they were loved by everyone! Thanks for trying them and leaving a review!