Soft and Chewy Monster Cookies

Our ultra soft and chewy monster cookie recipe is packed with peanut butter, oats, chocolate candies, and chocolate chips. Quick and easy to make, and easy to customize, this flourless cookie recipe is sure to be a hit with your family and friends!

Baking yummy cookie recipes is my go-to comfort, and my go-to treat. I’ve made a variety of monster cookie recipes over the years, and this recipe is the culmination of years of tinkering and modifying and playing around to this recipe’s flourless monster cookie perfection.

Ingredients for Gluten Free Monster Cookies

• Salted butter. Butter adds richness, tenderness, moisture, and structure to our cookies, which is especially helpful in this flourless cookie recipe.
• Granulated Sugar AND Brown Sugar. We’re using a combination of both white sugar and brown sugar to create cookies with the perfect level of sweetness, moistness, and chewiness.
• Large eggs. Using whole eggs (versus using just an egg yolk or an egg white) helps provide structure, leavening, and moisture.
• Vanilla Extract. Adds depth of flavor in our cookie recipe.
• Creamy peanut butter. In addition to adding a nutty flavor, peanut butter contributes this cookie’s soft consistency and can contribute to a more delicate and crumbly texture too. While I love natural peanut butter, I’ve found it can be challenging to bake with. I tend to use JIF when baking because of having consistently good results with it.
• Salt. A little is used to help enhance the other flavors.
• Baking soda. Used as the leavening agent in our cookies, baking soda contributes to the wonderfully chewy texture in this recipe.
• Old-fashioned rolled oats. Oats add flavor, texture, and chewiness to our cookies. Old fashioned oats (also called rolled oats) will give the very best texture to your cookies, but in a pinch quick-cooking oats (NOT instant oats) will work for your cookies as well. You can learn more about the different types of oats and how to use them in this detailed informational post about oats.
• Semi-sweet chocolate chips AND milk chocolate m&ms. We’re mixing in both chocolate chips and m&ms for the ultimate monster cookie experience.

See the recipe card at the bottom of the post for ingredient measurements and full directions.

How to Make Our Monster Cookies Recipe

Preheat your oven to 350°F. Set out your baking sheets, optionally lining with parchment paper if desired.

Add the the butter, white sugar, and brown sugar to the bowl of a stand mixer with a paddle attachment (or into a large mixing bowl.

Cream the butter and sugars together with low to medium speed (or using a wooden spoon if mixing by hand) until the mixture is lighter and fluffy (it will still look a little grainy).

Add in the eggs and stir to combine into the butter and sugar mixture.

Next, stir in the vanilla extract and peanut butter until well combined.

Add the salt, baking soda, and rolled oats to the mixture and stir to combine.

Gently mix in the chocolate chips and m&ms until well dispersed through the dough.

Using a medium cookie scoop (equal to about 2 Tablespoons worth of dough), scoop dough balls onto the cookie sheets, keeping them about 2 inches apart.

Optionally, press and additional 3-5 m&ms and/or chocolate chips on top of each dough balls.

Bake for 9-12 minutes until the edges look set and the cookies look golden brown.

Remove them from the oven and allow to set on the cookie sheet for a few minutes. Then transfer to a wire cooling rack to cool completely.

Variation Ideas for These Peanut Butter Monster Cookies with Oatmeal

Make them festive with seasonal m&ms! Halloween monster cookies, Christmas monster cookies, Valentines monster cookies, Easter monster cookies, 4th of July monster cookies… you can do them all!

Change your mix-ins. My go to is half m&ms and half chocolate chips for a total of 1 Cup of mix-ins for a single batch as noted in the recipe card, but this is where you can have fun! You can try some chopped nuts like pecans or walnuts, shredded coconut, mini Reese’s, raisins, etc.

Possible Dietary Restrictions?

This recipe is vegetarian and gluten-free as written. If serving to someone with celiac just be sure to confirm the oats you’re using are certified to be gluten-free, and while most semi-sweet chocolate chips are gluten free you can also purchase a chocolate chip brand (like Enjoy Life chocolate chips) that is certified to be gluten free if you’re concerned.

Storage Information

Store fully cooled cookies in an airtight container at room temperature for up to 5 days (if they last that long!).

Freezing Before or After Baking

To freeze before baking: Make the cookie dough as directed in the recipe card. Line a baking sheet with waxed paper, and like you would before baking, scoop dough into balls. Place dough balls onto the lined baking sheet, without them touching, and chill the pan in the freezer for 1 hour (this is called “flash freezing”). Once the cookie dough balls are cold and solid, place them into a large freezer bag.

When ready to enjoy, you can bake the frozen cookie dough balls directly from frozen! Place them onto a baking sheet as noted in the recipe card, and simply add an extra 2-3 minutes to the bake time.

I personally love this option and because having a freezer stash of cookie dough balls to bake later is THE BEST. That way you can have freshly baked cookies any time, and you can also bake off a smaller amount of cookies if you want!

To freeze baked cookies: Place fully cooled cookies into a freezer bag or air-tight container and store in the freezer for up to 3 months. When ready to enjoy, remove the cookies from the freezer and allow them to thaw overnight in the refrigerator.