Monster Cookie Bars

Monster cookie bars are chewy ooey gooey thick bars! They're loaded with peanut butter, m&m's, rolled oats, and chocolate chips! It's the kind of recipe you make when you don't feel like rolling out cookies but still want a soft oatmeal peanut butter cookie!

These monster cookie bars are basically like monster cookies but in bar form! They come together in 30 minutes to satisfy your cravings nearly immediately! If you don't have a cookie tray or don't feel like rolling out cookies, this is the perfect recipe to make.

These bars are full of rolled oats, creamy peanut butter, m&m's, and chocolate chips! It's made in one bowl, and no electric mixer is needed! Of course if you'd like to use one it does speed up the process.

For more cookie recipes, try Mini M&M Cookies, Cinnamon Pecan Chocolate Chip Cookies, or Brown Butter Oatmeal Chocolate Chip Cookies.

Jump to:

• Why this recipe works
• Ingredient notes
• Step by Step Instructions
• Expert baking tips
• FAQ
• Check out these recipes
• Monster Cookie Bars

Why this recipe works

Easy to make: No mixer needed and it comes together in one bowl.

Oatmeal bars: This recipe tastes just like a soft and chewy oatmeal cookie but in bar form.

Chocolate goodness: These bars are loaded with chocolate chips and mini m&m's! The best combo.

Perfect for any occasion: This recipe is super flexible for any occasion. The little monster eyes placed on top are the cutest for halloween, but you can leave them out or change it to any holiday sprinkles!

Kids friendly dessert: A fun halloween recipe to make with young kids that isn't too scary but rather 'cute'!

Ingredient notes

Scroll to view a few ingredients notes. Full recipe and measurements can be found in the recipe card below.

Butter – Unsalted butter works best. This will be softened to room temperature. Remove two hours before baking

Chocolate chips – I used semi-sweet, but mini or dark works too. Don’t use milk or it’ll be too sweet.

Dark brown sugar – This type of brown sugar carries more molasses than lighter brown sugars, which helps create chewy cookie bars.

Eggs – Must be room temperature. The egg yolk helps add extra softness and moisture. Remove from refrigerator two hours prior to baking.

Mini M&M’s – I bought mini M&M’s at my local grocery store. Sometimes they are tricky to find, so you may use regular sized too.

Peanut butter - Must be creamy peanut butter. Natural is too runny. Crunchy works as well!

Step by Step Instructions

Here is how to make and bake these monster cookie bars . You will need an 8×8 square pan lined with parchment paper, a large mixing bowl, a spatula, and a whisk.

Step 1: Mix the butter and sugars: In a large mixing bowl, cream butter, peanut butter, and both brown sugars until light and fluffy.

Step 2: Add in egg and vanilla. Whisk in the egg yolk, egg, and vanilla until smooth.

Step 3: Add in dry ingredients. Fold in flour, rolled oats, baking powder, and salt. The dough will be very soft.

Step 4: Toss in add-ins. Add in the mini M&Ms and chocolate chips.

Step 5: Press the dough into the pan and bake. Transfer the dough to the prepared pan and use a spatula to evenly spread it in the pan. Bake in the preheated oven for 20-21 minutes, or until the edges are a light golden brown.

Step 6: Decorate and slice. Once baked, add extra add-ins if desired. You can also decorate them for halloween using candy eyeballs for a cute monster look! Slice and enjoy!

Expert baking tips

Here are a few baking tips from my kitchen to yours

• Properly measure the flour by spooning the flour into the measuring cup. If you stick the measuring cup directly into the bag of flour, it will compact it and you will have more than you need. A digital scale will give you the most accurate results.
• Substitute the add-ins! You can use any kind of chocolate chips, toffee pieces, regular-sized M&M's, peanut butter filled M&M's, etc!
• Add the halloween decor eyes on after they've been baked and sliced.
• Soften the butter quickly by placing it in the microwave at 15 second intervals or into the oven at 170°F for 2 minutes.
• It's better to underbake than overbake. The bars will continue to bake as they cool.

FAQ

Can I use regular sized M&M's?

Yes!

Can I double this recipe?

Yes! Use a 9x13 pan when doubling.

Can I use quick oats?

Yes! But keep in mind the texture will change.

Can I use one type of brown sugar?

Yes. If you only want to use one type, make sure to use 1/2 cup. (Rather than 1/4 cup light and 1/4 cup dark).

How do I know they're done?

The bars will be a light golden brown on the edges. The middle will look soft. If you remove them from the oven immediately they will slightly deflate.

How do I store these monster cookie bars?

Keep on the counter for 3 days or refrigerated in an airtight container for up to 5 days.

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