Best Monster Cookies Recipe (Thick & Chewy)
These Monster cookies really are a wonderful treat. Loaded with M&M’s, chocolate chips, peanut butter, butterscotch, and oats.

Monster cookies have become a favorite in our house these days. There are always discussions about how many someone ate and how many are remaining.
Are monster cookies healthy? The oats make them healthy, right? Well, I’m going with “yes.”
Basically, monster cookies are peanut butter oatmeal cookies loaded with m&m’s, chocolate chips, and other add-ins.
What You’ll Need
You’ll need the basic staple stuff for cookies.
- Unsalted butter – If using salted butter you will want to reduce the salt in the recipe. I can’t really tell you how much to use because all brands have different salt quantities.
- Creamy peanut butter – Crunchy peanut butter is drier and too dense for these cookies.
- Brown sugar and granulated sugar – I always use dark brown sugar for a deeper molasses flavor.
- Eggs – Use room-temperature eggs.
- All-purpose flour, baking soda, and salt – The base ingredients for cookies.
- Cornstarch – This helps develop a more tender cookie.
- Old-fashioned oats – Old-fashioned oats work best in these cookies, it creates thick and chewy cookies.
- Mini M&M’s, mini semi-sweet chocolate chips, and butterscotch chips – The fun little nibbles that make up the best Monster Cookies recipe!
Tips
- Measure the flour correctly! Aerate, spoon, and swoop level.
- Always use room temperature eggs and dairy.
- Use the mini M&M’s and mini chocolate chips they make a big difference. But if you must you can certainly use the regular size M&M’s and chocolate chips.
- Use processed regular peanut butter it works best like Jiff or Skippy. Do not use all-natural peanut butter for this Monster cookie recipe.
- Use seasonal colored M&M’s. Check out our Halloween Monster Eye Cookies, so cute!
How to Make the Best Monster Cookies
These Monster cookies are not your average size cookie. They are large and oh so thick! Plan ahead and chill the dough overnight. This is the key to keeping their shape and stopping them from spreading.
In the bowl of a stand mixer, cream together the room temperature unsalted butter and 1/2 cup peanut butter until smooth.
Add the brown sugar & granulated sugar, creaming together until fluffy.
Add in the eggs and vanilla extract, beating well.
In a separate bowl, mix the baking soda, salt, cornstarch, and flour, until combined.
Then add the dry ingredient mixture to the wet ingredients. Stir in the old-fashion oats, butterscotch chips, chocolate chips, and M&M’s until just combined.
Cover and refrigerate the dough for at least 2 hours, up to overnight. (we refrigerate overnight)
Preheat the oven to 350 degrees F. Line 2 baking sheets with parchment paper or baking mat.
Drop heaping 1/4 cup-sized balls of dough onto the prepared baking sheets, about 2-3″ apart.
Bake for approximately 12-14 minutes, until golden brown. Cookies may appear slightly undone in the center; this is normal and they’ll continue to set as they cool.

See! Look at these giant Monster Cookies! So amazing!
We use the mini M&M’s because we prefer the smaller crunch but if you prefer the regular size go for it. I don’t mind.
Old-fashioned oats are best for this recipe. They hold up when baking, quick oats will make the cookies spread more during baking. Steel-cut oats won’t work here.
Be sure you are using old-fashioned oats, your baking soda is fresh, and your butter is at room temperature. Also, refrigerating the dough is essential. You want the butter to solidify so when baking it takes longer to melt, so the cookies don’t spread too much. But I’ve never had these cookies go flat.
Place the completely cooled cookies in an air-tight container or bag and store them at room temperature for up to 1 week.
Place completely cooled cookies in a freezer-safe container or resealable bag and freeze for up to 3 months.
More Cookie Recipes
- Old Fashioned Peanut Butter Cookies
- Oatmeal Chocolate Chip Cookie Bars
- Best Chewy Snickerdoodle Cookies
- Oatmeal Raisin Cookies

Best Monster Cookies Recipe
Ingredients
- 1/2 cup Unsalted butter room temperature
- 1/2 cup Creamy peanut butter
- 3/4 cup Dark brown sugar
- 1/4 cup Granulated sugar
- 2 large Eggs room temperature
- 2 teaspoons Vanilla extract
- 1 teaspoon Baking soda
- 1/2 teaspoon Salt
- 2 teaspoons Cornstarch
- 1 1/2 cups All-purpose flour
- 1 cup Old-fashioned oats
- 1 cup Mini M&M's candies
- 1/2 cup Mini semi-sweet chocolate chips
- 1/2 cup Butterscotch chips
Instructions
- In a large bowl cream together the butter and peanut butter until smooth.
- Add the brown sugar & granulated sugar, creaming together until fluffy.
- Add in the eggs and vanilla, beating well.
- In a separate bowl, whisk the baking soda, salt, cornstarch, and flour, until combined.
- Add the dry ingredients to the wet ingredients.
- Stir in the oats, M&M’s, chocolate chips, and butterscotch until just combined.
- Cover and refrigerate dough for at least 2 hours, up to overnight.
- Preheat the oven to 350 degrees F. Line 2 baking sheets with parchment or silicone liners.
- Drop heaping 1/4 cup-sized balls of dough onto the baking sheets, about 2-3" apart. (Roll into balls for best results.)
- Press a few extra M&M's on the top of the cookies. (this is not absolutely necessary)
- Bake for approximately 12-14 minutes. Cookies may appear slightly undone in the center; this is normal and they'll continue to set as they cool.
- Cool on the baking sheet for at least 5 minutes then transfer to racks.
Notes
You can also thaw in the fridge for about 2 hours and then bake as instructed.
Nutrition
Recipe inspired by TheGirlWhoAteEverything
This is now by go to recipe. I have used smarties, nuts etc always turns out great
Just what I was looking for!! I bake for a children’s charity & I’m sure these will be a big hit!! Thanks for sharing!
This is a great monster Cookie recipe! I have made it several times!
Your Monster Cookies will be a big hit with the little Monsters here. Your recipe looks awesome and thanks so much for sharing it with us at Full Plate Thursday. Have a great day and come back to see us real soon!
Miz Helen
My kids would love these! Thanks for sharing at Merry Monday! 🙂
These cookies look wonderful for those lazy afternoons where you can lounge around snacking, or anytime, really. 🙂 Love all the add ins!
Thank you they are really tasty! 🙂
Thank you for posting the recipe for these delicious cookies! Perfect for parties and gatherings. – Suzie
Thank you, Suzie! 🙂