Monster Cookies

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These are my favorite soft and thick Monster Cookies, made with peanut butter, oats, M&Ms, and chocolate chips. They are so easy to make and you don’t need to chill the dough!

Cookies topped with M&Ms and chocolate chips on a wire rack.

These delicious Monster Cookies became my favorite cookies to bake. They are so easy to prep and there is no chilling required. Loaded with oats, peanut butter, M&Ms, and chocolate chips, they will make a grate treat for the holiday season or a simple Sunday bake.

These cookies will be a perfect addition for the Christmas Cookie party, along with Cranberry Orange Biscotti, Snickerdoodle Cookies, Almond Spritz Cookies, Chocolate Chip Pecan Cookies, and many others.

And if you are making them for Halloween, I love to decorate them with some eyeball candies on top and serve with Halloween Sugar Cookies and Halloween Rice Krispie Treats.

Why you will love this recipe

Easy to make. Because we don’t need to chill the dough for this recipe, it’s really easy to prep and bake this cookies.
Has your favorite ingredients. Who doesn’t like oats, peanut butter, M&Ms, and chocolate chips? These cookies have it all!
Fun for kids. Thanks to colorful M&Ms, it will be fun to make this treat with your kids.
Make ahead. I love making the dough ahead of time and keep it in my freezer. Check out the freezing instructions below in the recipe.

Ingredients and Substitution

Butter. When making cookies, we always want butter to be room temperature. So, when it’s mixed with the sugar, it will be easily blended and become light and airy.
Sugar. In this recipe, I use a mix of granulated and light brown sugar. Granulated sugar provides crispy edges, while brown sugar keeps the cookies soft and moist inside.
Peanut butter. You can use your favorite brand of creamy peanut butter. Brands like Skippy and Jif work very well.
Egg. Similar to butter, it has to be room temperature.
Vanilla extract. I always like to add a touch of vanilla extract for extra aroma.
All-purpose flour. Make sure you measure the flour correctly. To do so, scoop the flour into a measuring cup and scrape the back of the butter knife across the top to level it.
Oats. I prefer to use old-fashioned rolled oats for more texture, but you can also use 1-minutes oats.
Salt. A magic ingredient that helps to balance the sweetness
M&Ms. I like to use classic M&Ms. You can also use flavored ones, like with peanut butter.
Chocolate Chips. You can use dark, semi-sweet or milk chocolate chips.

How to make it

Preheat oven to 350°F. Line a large baking sheet with parchment paper and set aside.

In a mixing bowl, add dry ingredients (1 cup all-purpose flour, ½ cup rolled oats, ½ tsp baking soda, ¼ tsp salt). Mix and set aside.

Process photos of mixing flour with rolled oats.

In a separate large mixing bowl, add ½ cup room temperature unsalted butter, ⅓ cup light brown sugar, and ¼ cup granulated sugar. Using a stand or hand mixer, beat well for about 5 minutes, until it becomes light and airy.

Process photos of mixing butter with sugar.

Add ½ cup peanut butter and mix again.

Add 1 large egg and 1 tsp vanilla extract. Beat again until well combined.

Process photos of mixing egg and vanilla extract with cookie dough.

Add dry ingredients and mix it on low speed until just halfway mixed.

Process photos of adding dry ingredients to cookie dough.

Then add ½ cup M&Ms and ½ cup chocolate chips and mix until combined. Don’t overmix.

Process photos of adding M&Ms and chocolate chips to cookie dough.

Using an ice cream scoop or a regular spoon, scoop out about 2 tbsp of cookie dough, roll it in a ball and place on the baking sheet with parchment paper.

Slightly press to flatten and top with a couple of M&Ms and chocolate chips.

Bake at 350°F for about 11-13 minutes or until the tops are just set.

Take them out of the oven and let sit on the counter on baking sheet for another 10 minutes before transferring to a wire rack.

Monster Cookies on a baking sheet before and after baking.

Tips for best results

Ingredients temperature. To make sure that all the ingredients blend well with each other, they should be room temperature (especially butter and eggs).
Cream butter and sugar. The trick to make the cookies perfectly soft is to beat the butter with sugar on high speed for about 5 minutes. The mixture should become light and airy.
Baking time. Depending on your oven, baking sheet, and the size of the cookies, the baking time should take between 11-13 minutes. The tops should be just set but still very soft. They will continue to “bake” while resting on the baking sheet on the counter. Also, that will ensure them to stay soft and not dry.

Storage and Freezing

How to store. You can keep monster cookies in an air-tight container on a countertop for 3-4 days.
How to freeze. After they are completely cooled off, transfer them to an air-tight container or a freezer-safe bag and freeze up to 3 months.
How to freeze cookie dough. When freezing cookie dough, I like to roll it into balls first, place on a baking sheet and put in the freezer for 30 minutes to harden (this way they won’t stick to each other). Then transfer to an air-tight container or a freezer-safe bag and freeze for up to 3 months. To thaw, just leave in the fridge overnight. Take it out of the fridge and leave on the countertop for about 20 minutes before baking.

Cookies topped with M&Ms and chocolate chips on a baking sheet.

Frequently Asked Questions

What Monster Cookies are made of?

Classic monster cookies should contain these four main ingredients: oats, peanut butter, M&Ms, and chocolate chips. Although, today you can often see different variations that use other add-ons.

Do you need to refrigerate Monster Cookie dough?

No. These cookies are not very spreadable, which means you don’t really need to refrigerate the dough.

Why are my cookies dry?

Most likely you over baked them. When they are done, the top of the cookies should be just set but still very soft. They will continue to set when you take them out of the oven and let sit on the counter for 10 minutes.