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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.
Can I make this dough the night before and store in fridge over night or will they not bake properly?
Yes, the dough can be made ahead and refrigerated overnight. Just let it sit at room temperature for a bit before baking so the cookies bake evenly.
Love these! So do my nephews who requested these instead of others they like!
hello, thanks for posting. I was about to bake these but saw that your metric x2 and x3 converter is converting. It’s nothing big but would be nice it worked.
Yes I had this same issue with the metric conversion so I’m not sure I got the right amount of sugar in, but they did bake up beautifully!
Why did my cookies not flatten or spread out?? They came out in little balls just as they went in.
That usually happens when there’s a little too much flour or the dough is too cold, so it can’t spread. Try measuring the flour lightly and using room-temp butter next time
Everything, butter,eggs, etc. was room temperature but I will try again. They were still delicious
I’ve made this recipe multiple times and they always turn out perfect. This time they didn’t spread as much either. I use room temp everything and don’t chill the dough. I did use ceramic baking pans this time…Not sure what happened. They still tasted the same and after the first batch I did flatten them a bit before putting them in the oven
You can pick the pan up and drop towards the end of cooking and that will help them spread.
I made these again…. I had forgotten about them. My recipe was printed from before the updated 2024. Everyone loved them that I blessed with them. Even got some people asking for the recipe!
I’m super bummed. Wanted to make these “monster” cookies for my daughter’s Halloween party. I “doubled” this recipe and followed the grams (since that is more accurate) and the cookies were way off and thin, oily. I looked at the recipe after I baked them off and saw that your grams do not double when you click 2x. Please fix 🙁
This happened to me when I halved the recipe in print view. The flour and oat gram equivalents didn’t auto-halve, so I ended up with 12 lovely flour pucks. Ironically, I had decided to start measuring ingredients in grams on a scale when I bake so as to get more reliable results! Lol
I made these cookies this afternoon with my 10 year old twin grandchildren.
They had a fun time measuring out all the ingredients and sampling some of the M&Ms and chocolate chips to make sure they tasted all right before we added them!!
These were excellent cookies which made right on the two dozen mark with just a little over to eat raw.
The oomies kept their shape well and were so good!!
Can these be frozen
I freeze cookie dough after I flash freeze the dough balls. Allow a few minutes when baking frozen cookie dough.
Are these all People commenting for real. They are not. Mentioning that in process it is mentioned to Mix eggs. But in recipe there is no eggs. How you guyz made it.
I followed the recipe and used 2 whole eggs and 1 egg yolk, adding them as usual to wet ingredients, after butter and sugar, mixing one at a time. Just standard dough instructions.
It says right in the recipe, 1 egg
It literally says 1 egg right after the peanut butter!!!!
My son doesn’t like peanut butter. What could we replace it with?
You could swap the peanut butter with another nut or seed butter—like almond, cashew, or even sunflower seed butter if you want it nut-free. All work great in this recipe!