Best Monster Cookies Recipe (Thick & Chewy)

These Monster cookies are a wonderful treat. Loaded with M&M’s, chocolate chips, peanut butter, butterscotch, and oats. Crispy edges with a luscious soft and chewy center.

Why You’ll Love These

This easy Monster cookies recipe has become a favorite in our house these days.

They are thick and chewy monster cookies loaded with everyone’s favorite chocolate chips, M&M’s, and butterscotch chips.

They are simple to make, freeze, and bake anytime you have a craving.

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.

Some of our other favorite cookie recipes to make are Italian Butterball Cookies, Hello Dolly Cookies Recipe, Chewy Snickerdoodle Bars, Lemon Sandwich Cookies, and Old Fashioned Peanut Butter Cookies.

What are Monster Cookies?

Basically, monster cookies are peanut butter oatmeal cookies loaded with m&m’s, chocolate chips, and other add-ins.

Monster cookies recipe ingredients on a dark surface.

Ingredients Needed

See the recipe card below for a full list of ingredients, measurements, and instructions.

Unsalted butter – If using salted butter you will want to reduce the salt in the recipe. I can’t 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.
Dark 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 – Base ingredients for cookies.
Cornstarch – This helps develop a more tender cookie.
Old-fashioned oats – Old-fashioned oats work best in these cookies, they create thick and chewy cookies. Quick-cooking oats are smaller and create a finer texture in 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!

How to Make the Best Monster Cookies

In the bowl of a stand mixer or large mixing bowl, 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 until combined.

Peanut butter and unsalted butter beat together in a metal mixing bowl.

Eggs and vanilla beat into the creamed ingredients for monster cookies.

In a separate medium 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.

Dry ingredients mixed into the wet ingredients until some dry flour still remains.

Monster cookie dough in a metal mixing bowl.

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!

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.
Place a few extra m&m candies on top of the cookie dough balls before baking if desired.
Using processed regular peanut butter like Jiff or Skippy works best. 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!

Variations

Skip the chilling time 14-16 minutes. Just know that they will have much better flavor after chilling the dough.
Don’t like butterscotch? Substitute white chocolate chips.
Substitute peanut butter mini M&M’s for chocolate M&M’s.
For more peanut butter flavor use Reese’s pieces.
These are giant cookies! You can make them smaller using a 1-inch cookie scoop and reduce the cooking time to 10-12 minutes.

FAQs

What kind of Oats to Use

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.

Why did my cookies go flat?

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.

Storing

Place the completely cooled cookies in an air-tight container or bag and store them at room temperature for up to 1 week.

Freezing

Place completely cooled cookies in a freezer-safe container or resealable bag and freeze for up to 3 months. Or freeze the dough balls until hard and place them in a freezer safe container. To bake from frozen you may need to add a few extra minutes to the baking time.

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