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These Thick and Chewy Monster Cookies are loaded with peanut butter, oats, M&M's and chocolate chips. They’re a cross between a chewy oatmeal chocolate chip cookie, and a peanut butter cookie, and they’re sure to be a huge hit with family and friends.
I LOVE making cookies, and since I don't usually have fresh-baked cookies available on the spot, I like to freeze them for when friends come over or when we just want a little treat. In my freezer currently are Jumbo Chocolate Chip Cookies, Red Velvet Sandwich Cookies, and Chewy Pumpkin Chocolate Chip Cookies. Who wants to come over?!
Monster Cookies
Don't ask me to choose a favorite type of cookie because I just wouldn't be able to! There are too many fun variations. These Monster Cookies are always popular and I love the great texture from the oats and the subtle peanut butter flavor.
Why are they called Monster Cookies?
There’s not an exact answer for why these cookies are called “Monster” Cookies. Some people think it’s because they look like monsters, with their bumpy texture and fun colors. I like to think it’s because they’re stuffed with so much “stuff”, making them the “monster” of all cookies.
Whatever the reason, all Monster Cookies have these ingredients in common: peanut butter, oats, chocolate chips and m&m chocolate candy.
How to make Monster Cookies:
- Cream the butter and sugars. Use REAL butter and cream it with the sugar for at least 2-3 minutes until really light and fluffy. This is adding air to the mixture and is the base for the texture we want in our cookies.
- Mix wet ingredients. Add the peanut butter and mix well. Add egg and vanilla and mix.
- Measure flour properly and mix dry ingredients. When measuring the flour be sure to fluff it a bit first, allowing air to fill in (like sifting) before you spoon it lightly into the measuring cup. Stir together the flour, oats, salt, baking powder and baking soda. Stir into wet mixture with m&m's and chocolate chips.
- Slightly under-bake. Bake at 350, being careful not to over bake the monster cookies. The tops will look just set and they will continue to harden and set up as they cool on the baking sheet.
How do I keep my cookies from spreading?
During baking, cookies naturally spread, but the key is to make sure they don't spread too much. To keep your monster cookies from spreading, be sure to use exact measurements (no guesstimating) and use room temperature ingredients, particularly the butter and eggs. You can also stop cookies from getting flat by chilling the dough for 15-30 minutes before baking.
Storage and Freezing Instructions:
These cookies will keep well in an air-tight container for 1-2 days, or you can freeze the cookie dough or baked cookies. To freeze them after they’re baked, allow them to cool completely and store them in a freezer safe container for up to 3 months. Freeze cookie dough balls in a freezer safe container and when ready to bake, place the frozen cookie dough on a baking sheet and add 2-4 minutes to the baking time.
CONSIDER TRYING THESE POPULAR COOKIE RECIPES:
- Jumbo Chocolate Chip Cookies
- Super Soft Sugar Cookies
- Triple Chip Blondies
- M&M Cookie Bars
- Chocolate Mint Cookies
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Thick and Chewy Monster Cookies
Equipment
- Stand Mixer optional
Ingredients
- 1/2 cup butter
- 1/2 cup granulated sugar
- 1/2 cup light brown sugar
- 1/2 cup peanut butter
- 1 egg
- 1 teaspoon vanilla extract
- 1 cup all-purpose flour
- 1 1/4 cups old-fashioned rolled oats
- 1/4 teaspoon salt
- 1/2 teaspoon baking powder
- 1/2 teaspoon baking soda
- 3/4 cup M&M candies
- 1/2 cup semi-sweet chocolate chips
Instructions
- Preheat oven to 350 degrees F.
- Cream the butter and sugar together really well—at least 2-3 minutes until light and fluffy.
- Add peanut butter and mix well. Add egg and vanilla and mix.
- In a separate mixing bowl stir together the flour (be careful to measure correctly, spooning the flour into a measuring cup, then leveling off), oats, salt, baking powder and baking soda.
- Add to the wet mixture and mix to combine. Stir in chocolate chips and M&M’s.
- Bake at 350 degrees for 10-12 minutes, or a little longer if you make them bigger than a 1 inch cookie scoop. Don't over bake--they will look just set.
- Remove them from the oven and allow them to cool completely on the pan.
Notes
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
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HAVE YOU TRIED THIS RECIPE?!
RATE and COMMENT below! I would love to hear your experience.
OMG, these cookies are to die for. 10/10 would recommend. the only part I regret is eating them all. haha 😅
How many tablespoons per cookie?? I wish she would clarify the instructions.
I should have never made these cookies because they are so so delicious and I will eat them all!!
Every year I do a “bake off” where I try several recipes of the same type of cookie. This year was monster cookies, and this came out the winner! Best of the top four recipes on the internet. Thanks for sharing!
BEST MONSTER COOKIES EVER! They’re crisp on the outside and chewy on the inside. We used the pack of M&M’s with peanut, peanut butter, and regular in it and it was a great choice.
I love monster cookies so much and these are delicious. Nice and chewy they don’t get hard if they sit out or in the fridge. They’re literally perfect.
I have made this recipe so many times and decided it was time to comment. These are the best monster cookies. thank you. we make them all the time.
These are incredible. Have you tried any variations adding protein powder?
Love that you’re loving them! 🙌 I haven’t tested them with protein powder yet, but you can try swapping out about 1/4 cup of the flour for vanilla protein powder. Start small—too much can make them dry or cakey. A little extra peanut butter or a splash of milk can help if the dough feels stiff. Let me know if you experiment!!
I thought these were horrible! So dry!
Wondering where you went wrong – maybe creaming the butter too long or when you added the peanut butter? I’m thinking you could’ve over mixed after the oats or maybe you cooked them too long at a lower temperature? Please share when you figure out what mistakes you made so we can all learn!!!
I also was expecting Soft & Chewy but got dry & crumbly. Pretty disappointed. Been baking app 50 years. When I try recipe for first time I follow it exactly. Thought the dough was a little dry but didn’t do anything. Wish I would’ve.
My granddaughter is allergic to tree nuts, would I get the same results using sunbutter instead of peanut butter?
Yes, you can sub SunButter for the peanut butter—just note it might make the cookies a bit darker and slightly more moist. Still totally delicious and perfect for a nut-free treat your granddaughter can enjoy!
These monster cookies recipes are absolutely irresistible! The combo of peanut butter, oats, and M&Ms is always a hit in my house.
PSA: If you use the 2x button, it does not update the grams. So if you’re using a scale be careful!
I’m so glad I realized this also!!! But they were delicious!!!
I wonder how they will turn out if I use monster mix ?
Love them! These turned out perfectly 👌 And I’ve tried a few different monster recipes. Thank you! Having the measurements in grams is helpful, too. Less room for error 🙂
Made this for the first time today and they were very good. Would not change anything. My question is. Can you make the cookie dough the night before and refrigerate for baking the next morning?
Yes! You can absolutely make the dough the night before and refrigerate it. Just cover it tightly and let it sit at room temp for 15–20 minutes before scooping and baking the next day.
Great recipe! I used the equivalent of mini-M&Ms (my parents brought back a bulk bag from Amish country) and doubled the recipe for more cookies. My cookie scoop was an inch and a half, so I baked for 15 minutes, and they turned out perfect! Just lightly golden brown on the very edges and soft in the middle. Will be keeping this one in my favorites folder to make again!
I also used mini M&M’s and instead of salted peanuts, I added roasted, salted walnuts. Such a great one cookie treat! The dough was so creamy and light.
Wow! This recipe is delicious! My cookies came out perfect! I used Adam’s 100% Natural peanut butter/crunchy and it was creamy. I added a Tbsp of vanilla instead of a tsp. I used mini chocolate chips and m&m’s. I will be using this recipe again and again!