Chewy Monster Cookies with Peanut Butter and M&M’s
Can’t decide between a peanut butter cookie, an oatmeal cookie and a chocolate chip cookie? These chewy monster cookies are all three in one, with chunky peanut butter and oats loaded up with chocolate chips, peanut butter chips and mini M&M’s. They’re flourless, they mix up in one bowl and they bake in about 10 minutes.

A Quick Look At The Recipe
- Recipe Name: Monster Cookies
- Serves: 4
- Main Ingredients: + 1/2 cups chunky peanut butter, dark brown sugar, white sugar, softened butter, eggs, vanilla, oats quick, baking soda
- Why You'll Love It: These are The Monster Cookies Everyone Loves because they have just the right ingredient for each and every person yet they are also easy to make!
They’re called the monster cookies everyone loves in our house because there’s a little something for every person in each bite. Swap in orange and brown M&M’s and they’re right at home on a Halloween party platter next to big chewy Halloween candy cookies.
Why These Monster Cookies Are So Chewy
Oats stand in for flour here, so the cookies bake up thick and chewy, and a full cup and a half of chunky peanut butter adds richness plus a little crunch. Using both dark brown and white sugar gives them crisp edges and soft centers, and letting them rest on the pan for 5 minutes lets the middles finish setting.
Ingredients for Monster Cookies

Chunky peanut butter: It adds texture, but creamy works if that’s what you have.
Quick oats: They hold the dough together in place of flour and keep the cookies chewy.
Mix-ins: Chocolate chips, peanut butter chips and mini M&M’s are the classic trio. Nuts, butterscotch chips or chopped candy bars work too.
You’ll find the exact amounts in the recipe card below.
Helpful Tips Before You Start
- Use a cookie scoop or roll golf ball-size portions so the cookies bake evenly.
- Press a few extra M&M’s on top of each dough ball before baking so they look bakery-pretty.
- Grease your cookie sheets well. If yours are worn out, I love these Caraway baking sheets.
- Let the cookies rest on the pan for 5 minutes before moving them, since they’re soft when they first come out.
How to Make Monster Cookies

1Mix the Dough
Preheat the oven to 350°F. Add the peanut butter, sugars, butter, eggs, oats, baking soda, vanilla and salt to a large bowl.

2Add the Mix-Ins
Mix well with an electric mixer, then add the chocolate chips, peanut butter chips and M&M’s and mix until blended.

3Scoop the Cookies
Roll the dough into golf ball-size rounds and set them 2 inches apart on greased cookie sheets.

4Top with M&M’s
Press a few extra M&M’s on top of each cookie.

5Bake and Cool
Bake for 10 to 12 minutes. Let them cool on the pan for 5 minutes, then move them to a rack.
Serving and Storing
Pack them in lunchboxes, take a plate to a bake sale, or set them out for a Halloween party with white chocolate candy corn cookies and ghost meringue cookies. You’ll find more ideas in our list of easy Halloween treats and desserts, and a glass of cold milk is all you need on the side.
Keep them in an airtight container at room temperature for a few days.
Monster Cookies FAQs
Are monster cookies gluten-free?
There’s no flour in them, so they can be, as long as you use oats labeled gluten-free and check your candy and chips.
Can I use old-fashioned oats?
Quick oats give the softest, most even texture. Old-fashioned oats work but make the cookies a little chunkier.
Why are they called monster cookies?
They’re loaded with a little bit of everything, from peanut butter and oats to chocolate chips and candy, which makes them big, hearty “monster” cookies.

Chewy Monster Cookies with Peanut Butter and M&M’s
Ingredients
- 1 1/2 cups chunky peanut butter
- 1 cup dark brown sugar
- 1 cup white sugar
- 1/2 cup butter 1 stick, softened
- 3 eggs
- 1 tsp vanilla
- 4 cups quick oats
- 2 1/2 tsp baking soda
- 1/2 teaspoon salt
- 1 cup semi sweet or milk chocolate chips
- 1 cup mini M&M’s plus extra for topping
- 1 cup peanut butter chips
Instructions
- In a large mixing bowl combine peanut butter, sugars, butter, eggs, oats, baking soda, vanilla and salt. Mix well with an electric mixer.
- Add in all other ingredients and mix again until well blended.
- Form dough into golfball size cookies and place two inches apart on greased cookie sheets.
- Bake at 350 for 10-12 minutes. Let cool 5 minutes before removing from pan. Enjoy!

These are really, really good! Will definitely be my new go to cookie recipe.
I am so glad to hear that you liked them Laura!! Have a great day! 🙂
Hey, Christy! Made these last week for my husband’s college classes. They were a big hit every time, and we even had a few left over for us. They were super! Have a blessed day!
Oh WOW!!! That just made my day Mary!! I hope you have a blessed day as well!
Christy, thank you so much for this recipe! By using gluten free oats, this was a perfect gluten free cookie for my kiddos! Most GF cookies taste weird and are tricky to make. These were wonderful! You are the best! My kids are loving them.
I am so glad to hear they worked out and tasted great!!!
These are awesome cookies. A friend of mine says they are the best cookies I have ever made and I bake alot, so that is a high compliment. The only thing I did different — I didn’t add the M&Ms. No one missed them. The funny thing about them, though, is they puffed up really big, so when I took them out of the oven, I gave each one a little pat to mash them down some!
Oh WOW, what a compliment indeed!! I am so glad to hear they were a hit!!
I used 2 mini m&m canisters, so it was a little less than a cup. Me personally, I’d rather have the scotch bars. I’m not crazy about chocolate chips, I know, a rarity for a woman. But the family loved them. The recipe yielded almost 5 dozen! That was a cookie jar, and then some.
I have a cookie eating family, so I’m going to try these. I could only find small containers of mini m&m’s…$1 for 1.77 oz. I bought to JUST THIS TIME. I am sure Christy would say “use whatever you have on hand”, or “whatever cranks yer tracker”. Where do you find mini in large quanities?
Who doesn’t love monster cookies, the absolute best think to get kids interested in baking!
Very true Lily!! 🙂