Soft and chewy Monster Cookies are an irresistible combination of peanut butter, chocolate chip oatmeal and M&M cookies. Pretty much the best treat! Kids and adults love these and they’re so perfect for parties, after school snacks and special occasions.

monster cookies with M&M's

I created these Monster Cookies last Christmas and after several tweaks, this might just be my favorite dessert ever. A classic monster cookie recipe is basically a peanut butter oatmeal cookie that’s filled with colorful candies and chocolate chips. They come out of the oven soft, chewy, and overflowing with M&M’s and chocolate chips! What’s there not to love?!

My kids are constantly requesting these! And they’re great to make for a variety of occasions – birthdays, parties, potlucks, family gatherings, picnics or just a yummy after-school treat. They’re also easy to change up, for the holidays, with all the different varieties of M&Ms! Check out these Valentine Monster Cookies!

What We Love About This Recipe!

  • Add-ins. Peanut butter, oats, M&M’s and chocolate chips all come together for the BEST Monster Cookie!
  • Feeds a crowd. This recipe makes about two dozen cookies! You’ll have plenty for holiday cookie tins, lunchboxes, class parties and STILL have lots left to enjoy at home! Need even more for a bake sale or party? Simply double or even triple the recipe.
  • Freezer-friendly. These are a great candidate for the freezer. You can either freeze the dough or you can freeze the cookies once they have been baked. This means fresh, homemade cookies in a moment’s notice!
  • Simple ingredients. Aside from grabbing the candy and chocolate chips from the store, the rest of the recipe uses pantry staple ingredients you probably have on hand.
big M&M oatmeal cookies

Ingredients needed

This Monster Cookies recipe combines all the basic cookie ingredients to create a thick and chewy base. Here’s everything you’ll need:

  • Butter. I recommend using unsalted butter, so that you have control over the amount of salt going into the recipe. If you only have salted butter available, simply omit the 1/4 teaspoon salt that the recipe includes.
  • Brown sugar. Use light or dark brown sugar to add sweetness and make theses babies chewy and moist.
  • Peanut butter. While it’s great for cooking and eating, natural peanut butter isn’t ideal for this recipe. They will turn out too dry and crumbly. We do not recommend crunchy style peanut butter for that same reason. Use processed creamy peanut butter such as Jif or Skippy.
  • Egg. One large egg will add structure, stability, and richness.
  • Vanilla. For flavor depth and a touch of sweetness. Use pure vanilla extract, not imitation.
  • All-purpose flour. Flour gives the cookies structure and makes them soft & tender with the perfect amount of chewiness.
  • Cornstarch. This is my “secret” ingredient to give add thickness and make them ultra soft.
  • Baking powder & baking soda. For the perfect rise and chewy texture.
  • Salt. A small amount of salt is VERY important to balance the sweetness and enhance other flavors.
  • Oats. Old-fashioned rolled oats provide lots of great texture.
  • Semi-sweet chocolate chips. These call for semi-sweet chocolate chips. We like to use mini chips, but feel free to use standard-sized or chunks. Our favorite brand for chocolate chips is Ghirardelli.
  • M&M candies. We used the regular milk chocolate M&M’s for that classic chocolate-y crunch. Feel free to try different flavors and change up the colors for another holiday!

How to make this recipe

This monster cookie recipe is simple, straightforward and will be your new go-to! Just follow these easy steps…

Please see the recipe card for the full, printable recipe with all of the details.

  • Prep. Preheat the oven and line your baking pans with parchment paper or a Silpat mat or other similar silicone baking mat.
  • Wet ingredients. In a large mixing bowl, using a stand mixer or a hand mixer with the paddle attachment, cream together the butter, brown sugar and peanut butter on medium to high speed until light and fluffy, about 3 minutes. Mix in the egg and vanilla, scrapping down the sides of the bowl as needed.
  • Dry ingredients. In a separate medium bowl, whisk to combine the flour, baking soda, cornstarch, baking powder, and salt.
  • Add dry ingredients to wet mixture. On low speed, gradually add in the dry ingredients and mix until just combined. Stir in oats, chocolate chips and M&M candies by hand. To make the dough more manageable to work with, allow it to sit for about 15 minutes. You can also chill the dough for about 30 minutes to make it less sticky.
  • Scoop dough balls. Use a large spoon or cookie scoop to make dough balls (mine were about 2 tablespoons full). Place the cookie dough balls onto a cookie sheet, leaving 2 inches in between each.
  • Bake. Place in the oven and bake for about 9-10 minutes. Do NOT overbake! Remove from the oven right when edges start looking set and golden. The centers may look slightly underbaked, but they will continue to cook even after they are removed from the oven.
  • Cool. Let cool on the baking sheet for about 5 minutes. Then, transfer them to a wire racks to continue to cool.
mixing ingredients in a large bowl to make monster cookies

Expert tips

There are tons of tips and tricks for baking the perfect cookies, but follow the suggestions below and you’re sure to have some amazing results!

  • Softened butter. Be sure your butter is softened to room temperature, so that it combines properly with the sugars. Room temperature butter is still a bit cool to the touch and it should indent slightly when you press on it with your finger. Take butter out of the refrigerator about 1 hour before beginning your recipe. Try this trick to soften butter quickly.
  • Measure flour correctly. Using a food scale is the most precise method for measuring ingredients, especially flour. If you don’t have one available, lightly spoon flour (don’t pack) into a measuring cup and without shaking the cup, use the straight side of a butter knife to level the flour across the measuring cup.
  • Fresh baking soda and baking powder. Be sure that your baking soda and baking powder are fresh before using, so these cookies rise properly! They lose potency over time. When I open a new can, I always write the date on the lid with a Sharpie. Discard the opened can after 6 months.
  • Bake on parchment or silicone. Parchment or, better yet, a silicone baking mat makes for the most perfect cookies. Greasing the baking sheet creates an overly greasy foundation, which could cause these to spread too much. Silicone baking mats will grip onto the bottom of your cookies to prevent them from spreading too much. The mats also promote even browning.
  • Don’t overbake. I recommend experimenting with a couple of cookies before baking the entire batch. This will help you find that sweet spot when it comes to bake time in your oven and your preferred level of doneness. As they cool, they will become more chewy than doughy.

For presentation, dot a few extra M&Ms and chocolate chips on each mound of dough before baking.

monster cookies stacked near a small jar of milk

Frequently asked questions

Why is it called a monster cookie?

These get the strange name because they’re a combination of so many ingredients, just like the Frankenstein monster! They’re also sometimes called “kitchen sink cookies” because they include everything but the kitchen sink!

Why did my monster cookies go flat?

These may spread too much if your oven is too hot or the baking soda or baking powder is expired. If you’re noticing the cookies turning out flat, chill them in the fridge for about an hour.

How do you make cookies more moist and chewy?

We’re adding cornstarch to produce soft and thick cookies. This recipe also calls for brown sugar instead of granulated sugar for a moister, softer cookie. 

Variations

This monster cookie recipe is pretty much perfect as-is, but feel free to get creative and experiment with your favorite ingredients! Here’s some options:

  • White chocolate. Swap out the semi-sweet chocolate chips for white chocolate chips or use a combination of the two types.
  • Nuts. Add in up to about 1 cup of chopped nuts if you want an extra crunch. Just be sure to use unsalted nuts, to avoid these cookies turning out too salty.
  • Sprinkles. Stir in 1/2 cup of sprinkles. You can even add more to the tops before baking.
  • Double the recipe. This recipe yields about 24 medium cookies. You can double the recipe if you need a larger batch for a party, gifting, or event.

Storing & freezing

  • Freezing dough. Scoop out balls of dough and place them on a sheet pan lined with parchment paper. Chill the dough in the freezer for 30 minutes. This will flash-freeze the dough, so the dough balls don’t stick together. Once firm, you can transfer them to a freezer-safe bag or container. Frozen dough will keep well for up to 3 months. Be sure to label your bag with the date.
  • Bake from frozen. Baking from frozen will work just fine. The tops of your cookies may darken a bit more, but they will still be delicious. Follow all of the cooking instructions, but add a minute or two onto the bake time.
  • Freezing baked cookies. Store in a freezer-safe container or baggie and freeze for up to 3 months.
  • Storing. Baked cookies will keep in an airtight container or zip-top baggie at room temperature for about 1 week, but I can’t imagine them lasting that long!
monster cookies on parchment paper

More cookie recipes

Looking to do a little baking? Give our other family-favorite recipes a try:

If you try these, let me know! Leave a comment and if your family loves them as much as mine does, be sure to give it a five star ⭐️ rating! Also, tag @kimscravings on Instagram with a picture of your creation. It’s so fun to see what you’re cooking! Be sure to subscribe to our mailing list to receive more healthy delicious recipes straight to your inbox. 

monster cookies with M&M's
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Monster Cookies

Soft and chewy Monster Cookies are an irresistible combination of peanut butter, chocolate chip oatmeal and M&M cookies. Kids and adults love these and they're perfect for parties, after school snacks and special occasions.
Author: Kim

Ingredients

  • ½ cup (1 stick or 115g) unsalted butter, slightly softened
  • 1 cup (200g) packed light or dark brown sugar
  • ½ cup (125g) creamy peanut butter, not natural style
  • 1 large egg
  • 2 teaspoons vanilla extract
  • ¾ cup (94g) all-purpose flour
  • 1 teaspoon baking soda
  • 1 teaspoon cornstarch
  • ¼ teaspoon baking powder
  • ¼ teaspoon salt
  • cups (129g) old-fashioned oats
  • 1 cup (180g) semi-sweet chocolate chips, I like using mini chips
  • 1 cup (170 to 200g) M&M candies, any size or variety

Instructions 

  • Preheat oven to 350ºF and line 2 large baking sheets with parchment paper or silicone baking mats. In a large bowl, cream together the butter, brown sugar, and peanut butter with a hand or stand mixer until light and fluffy, about 3 minutes. Mix in the egg and vanilla, scraping down the sides of the bowl as needed.
    adding egg and vanilla to cookie dough batter
  • In a separate bowl, add the flour, baking soda, cornstarch, baking powder, and salt; whisk to combine. With the mixer on low speed, slowly add the flour mixture to the wet ingredients and mix until just combined. Stir in the oats, chocolate chips, and M&M candies by hand. The dough will be a bit soft and sticky.
    mixing oats, chocolate chips, and M&M's with cookie dough batter
  • To make it more manageable to work with, allow the cookie dough to sit for 15 minutes – the oats will absorb some moisture, making the dough easier to work with. It's not necessary, but you can also chill the dough for about 30 minutes to make it less sticky. Drop the cookies by heaping spoonfuls onto the prepared cookie sheets, about 2 tablespoons of dough per cookie, leaving 2 inches in between cookies. For presentation, you can dot a few extra M&Ms and chocolate chips on each mound of dough before baking.
    combining M&M's in cookie dough
  • Bake for 9-10 minutes, or until the cookies are just starting to brown around the edges and the top still looks slightly undercooked. Do not over bake – cookies will continue to bake on the cookie sheet. Remove from the oven and cool for 5-10 minutes on the baking sheet before moving them to a wire rack to cool completely. Cookies will firm up as they cool.

Notes

  • Storage. Cookies can be stored in an airtight container, at room temperature, for up to one week.
  • Freezing Instructions. Cookie dough will freeze well for up to 3 months. See post for more detailed instructions. Baked cookies will also freeze well for up to 3 months, thaw to room temperature before serving.
  • Reheat cookies. Microwave until warm and cookies will taste just like they were freshly baked!
Serving: 1cookie, Calories: 225kcal, Carbohydrates: 26g, Protein: 4g, Fat: 12g, Saturated Fat: 6g, Polyunsaturated Fat: 1g, Monounsaturated Fat: 3g, Trans Fat: 1g, Cholesterol: 19mg, Sodium: 107mg, Potassium: 120mg, Fiber: 2g, Sugar: 18g, Vitamin A: 151IU, Vitamin C: 1mg, Calcium: 32mg, Iron: 1mg

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