The best thick and chewy monster cookies. Chewy cookies made up of peanut butter, oats, chocolate chips, and m&m's. Whats not to love!
These cookies are a huge hit amongst family and friends. If you've never had a monster cookie I highly recommend giving them a try! They're easy to make, store well, and are fun! My two young children loved making them too. They thought using m&m's was a real fun treat!

How to Make Monster Cookies
Start by preheating your oven to 350F and lining your baking pans with parchment paper.
In a large bowl on stand mixer beat butter and sugars together until light and fluffy. This usually takes about 3 minutes. Add in the peanut butter and mix until smooth. Mix in the eggs and vanilla extract.
In a separate medium sized bowl whisk the flour, salt, and baking soda together. Add the dry ingredients, as well as the oats, to the wet and mix until combined. Fold in the chocolate chips and m&m's.
Scoop 3 tbsp sized balls of dough and place them on a baking sheet 2 inches apart. Add the extra m&m's on top of the cookie dough balls.

Bake 9-10 minutes or until the bottom of the cookies are a golden brown. The top may still seem undercooked but the cookie will stiffen up after cooling. Cool cookies for 5 minutes on the pan before moving to cool to room temperature.

Tips of Making Perfect Monster Cookies
- Use parchment paper to line your pans. Using cookie spray or butter will make the cookies greasy.
- Do not use melted butter, if anything you want your butter to be on the colder side. Using melted butter will cause the cookies to spread to much and become flat.
- If heating butter in the microwave to soften it first cut it into small pieces, heat for 12 seconds, and touch with finger. The butter should feel soft but not make a large indent with your finger. If not heat for another few seconds. It is better to be slightly cold than melted.
- Spoon and level the flour means scooping the flour into the measuring cup using a spoon and then levelling off the excess with a knife or your finger. This gets you the proper measurement of flour opposed to just scooping it out with the measuring cup.
- For chewy cookies do not over bake. Cookies may still seem soft in the middle but will harden up after cooling. Once the bottoms are a golden brown the cookies are done.
- If cookies lose their round shape you can fix them. As soon as they come out of the oven take a round cookie cutter, slightly large than the cookies, place it around the cookies and gently swirl it.

Bake them on your own or bake them with your kids, either way I’m sure you’ll love with these Thick and Chewy Monster Cookies!
If you make these cookies you can tag me on Instagram @jessiebakestreats and leave me a review below. I’d love to hear from you!
For more ideas you can follow me on Pinterest.

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Thick and Chewy Monster Cookies
Ingredients
Cookie Dough
- 1/2 C salted butter softened*
- 1/2 C white sugar
- 1/2 C brown sugar
- 1 C peanut butter creamy
- 2 large eggs at room temperature
- 1 & 1/2 tsp vanilla extract
- 1 C all purpose flour spooned and levelled **
- 1 tsp baking soda
- 1/4 tsp salt
- 2 C rolled oats also called old fashioned oats
- 3/4 C mini semi sweet chocolate chips
- 3/4 C mini m&m's
Topping
- 1/4 C mini m&m's for adding on top of the cookie dough
Instructions
- Preheat oven to 350 F and line baking pans with parchment paper.
- In a large bowl on stand mixer beat butter and sugars together until light and fluffy. This usually takes about 3 minutes.
- Add in the peanut butter and mix until smooth.
- Mix in the eggs and vanilla extract.
- In a separate medium sized bowl whisk the flour, salt, and baking soda together.
- Add the dry ingredients, as well as the oats, to the wet and mix until combined.
- Fold in the chocolate chips and m&m's.
- Scoop 3 tbsp sized balls of dough and place them on a baking sheet 2 inches apart. Add the extra m&m's on top of the cookie dough balls.
- Bake 9-10 minutes or until the bottom of the cookies are a golden brown. The top may still seem undercooked but the cookie will stiffen up after cooling.
- Cool cookies for 5 minutes on the pan before moving to cool to room temperature.
- Enjoy!
Danielle
Delicious! I’m glad I read your comment about taking them out of the oven before the centers are set, it made for the perfect chewy cookie
Jessie M
I'm so happy you liked them, thank you for letting me know :). Chewy cookies are always the best!
Janet
Can you freeze the dough? Or at least keep in fridge for a few days ?
Jessie M
You can freeze the dough. Scoop cookie dough balls out and place flat on a baking sheet and freeze for a few hours. Once frozen, transfer to a container or freezer bag. When ready to bake, place the frozen cookie dough on a baking sheet and add 2-3 minutes to the baking time.
Nina
Tried this recipe. But too many oats in my opinion. Half the oats and then you might be better off. My cookies seemed to be really crumbly
Jessie M
Sorry you did not enjoy the recipe. If they came out crumbly it could be that the flour might not have been properly measured or that the cookies were over baked.
Keryn
I have just made these cookies for the first time. They look amazing and taste even better. Thank you for sharing this recipe.