This quick and easy peanut butter oatmeal monster cookies recipe yields thick, chewy cookies studded with chocolate chips and M&M’s. Customize the M&M colors to match holidays, parties, or team colors.
You will love these Oatmeal M & M Cookies
This is a familiar cookie, but a reliable monster cookie recipe is a must-have for holiday baking and special occasions.
They’re dangerously good — when I updated this post I ate seven in a single day. No regrets.
Why we call it a “Monster Cookie”
These oatmeal-peanut butter cookies packed with chocolate chips and M&M’s feel like a cookie-sized hodgepodge — so “monster” seems fitting.
They’re full of mix-ins, not always uniform in appearance, and delightfully overstuffed.
Monster Cookies Recipe ingredients
This recipe is straightforward and doesn’t require chilling the dough, which makes it quick to prepare.
I developed this recipe starting from a classic chewy oatmeal cookie and adjusted amounts and technique to account for peanut butter and mix-ins.
For these oatmeal monster cookies, you will need:
• quick oats
• all-purpose flour
• baking soda
• ground cinnamon
• salt
• unsalted butter
• light brown sugar
• egg
• creamy peanut butter (not natural)
• vanilla extract
• M&M’s
• semi-sweet chocolate chips
Note: Use traditional creamy peanut butter (the kind with added sugar). Natural peanut butter won’t give the same texture.
How to make Monster Cookies
The dough is simply wet ingredients + dry ingredients + mix-ins.
After mixing, let the dough rest about 10 minutes so the oats absorb moisture. Scoop dough onto a lined baking sheet and gently press the tops to flatten slightly before baking.
These cookies don’t spread much because of the mix-ins. If you skip pressing them down they’ll still taste great but will look taller and more rustic.
How to serve Oatmeal M&M Cookies
I prefer them after resting a few hours when the center softens slightly, but they’re also delicious warm from the oven.
If you like a softer cookie, store them for a day and they’ll mellow even more.
How to store this Monster Cookies Recipe
Store baked cookies tightly covered at room temperature for up to 5 days. They will soften over time. You can freeze baked cookies up to 3 months.
Customize your recipe to fit any occasion
The best part of monster cookies is how easy they are to customize. Swap M&M colors for holidays, showers, or team events.
Try seasonal color schemes — red and green for Christmas, pastels for Easter, or team colors for game day. You can also add butterscotch, white chocolate, or extra peanut butter chips for variety.
Mix and match chips and candies until you find your favorite combination — and yes, color combos can feel different, so taste-test away.
Best Monster Cookie Recipe FAQs
If cookies flatten, your oven or kitchen may be warm. Chilling the dough briefly can help maintain shape.
Oatmeal cookies include a significant amount of oats alongside flour, adding distinct texture and flavor that sets them apart from standard cookies.
Looking for more oatmeal cookie recipes? Try chewy oatmeal raisin cookies or funfetti oatmeal cookies, or explore an oatmeal cookie collection for more ideas.
Monster Cookie (Oatmeal M & M Cookies)
Ingredients
- 2 cups (160g) quick oats (not old fashioned)
- ¾ cup (90g) all-purpose flour
- ¾ teaspoon baking soda
- ½ teaspoon ground cinnamon
- ¼ teaspoon salt
- ½ cup (113g) unsalted butter, melted
- ¾ cup (150g) firmly packed light brown sugar
- 1 large egg, at room temperature
- ½ cup (128g) creamy peanut butter (not natural)
- 1½ teaspoons vanilla extract
- ½ cup M&M’s
- ½ cup (85g) semi-sweet chocolate chips
Instructions
- Preheat oven to 350ºF (177ºC). Line a large baking sheet with parchment paper or a silicone mat.
- In a large bowl, whisk together the quick oats, flour, baking soda, cinnamon, and salt. Set aside.
- In a medium bowl, whisk melted butter and brown sugar until smooth. Whisk in the egg, peanut butter, and vanilla until combined.
- Pour wet ingredients into the dry ingredients and mix with a large spoon or rubber spatula. The dough will be thick. Fold in the M&M’s and chocolate chips. Let the dough sit about 10 minutes so the oats absorb moisture.
- Using a cookie scoop, drop scoops of dough onto the prepared baking sheet. Gently press down the tops to flatten slightly.
- Bake 10 minutes, until edges look set. Centers may look soft—this is fine. Cool on the baking sheet 5 minutes, then transfer to a wire rack to cool completely. Store in an airtight container up to 1 week. Baked cookies freeze up to 3 months.
Notes
- Quick oats: quick oats are essential; old fashioned oats don’t absorb liquid as well. If needed, pulse old fashioned oats in a food processor until finer.
- M&M’s: use small or mini M&M’s. Avoid larger peanut or peanut-butter M&M’s for this recipe.
Nutrition Disclosure
All nutritional values are approximate and provided as a courtesy. Changing ingredients or quantities will alter the estimates.
Calories: 178 kcal |
Carbohydrates: 21 g |
Protein: 3 g |
Fat: 10 g