Monster cookies are the best…a little chocolate, a little peanut butter, something chewy, something crunchy…and then you put it all in one cookie and call it a day. Yes, please.

I started making these when nothing in the pantry sounded good on its own. Too many options, not enough commitment (story of my life). But this is the kind of recipe that fixes all that. It uses what you already have, leans into the mix-ins, and somehow turns out better than whatever you were originally craving (which feels like a huge win).

Why You’ll Love These Peanut Butter Monster Cookies

These cookies are thick, peanut buttery, soft in the middle, a little crisp around the edges, and packed with chocolate and crunch, so every bite actually feels like something.

And the best part is, they’re super flexible. You can clean out the baking drawer, use what you have, skip what you don’t, and the cookies will come out like you meant to do it that way, haha.

Ingredient Notes

• Use room temperature unsalted butter for the best creaming. If you forget to take it out ahead of time, 10 seconds (unwrapped) in the microwave should do it. But make sure it doesn’t get too warm or the cookies will spread like crazy.
• You can use light or dark brown sugar for these cookies. I personally like to use dark brown sugar here for a little extra richness and chew. It just makes the cookies better, but light brown will work too.
• Use rolled oats over quick-cooking oats. Rolled oats hold their shape better during baking, giving the cookies structure and chew without turning to mush. Quick oats will make the cookies thinner and less substantial, but if that’s all you have, it’s better than nothing.
• Use smaller mix-ins for the best texture. Stick with mini M&Ms for this recipe. You can use mini or regular size chocolate chips, but avoid using jumbo chips. Oversized candies or chocolate chips can weigh down the dough and result in thicker, chunkier cookies that don’t spread like they should (they’ll probably look like misshapen hockey pucks actually, haha).

Step-By-Step Instructions

1. Preheat oven to 350°F and line 3 baking sheets with parchment paper.
2. In a large bowl (or in the bowl of your stand mixer), cream the butter, sugar, and brown sugar together with on medium speed for 1–2 minutes until light and fluffy.
3. Mix in the peanut butter, egg, and vanilla extract just until combined.
4. Add the flour, baking soda, and sea salt. Mix just until crumbly.
5. With a wooden spoon or spatula, fold in M&Ms, peanut butter chips, oats, and mini chocolate chips. Don’t overmix.
6. Using a 3 TBS cookie scoop, portion the dough onto baking sheets, 2 inches apart.
7. Bake for about 12 minutes, rotating the pan halfway through (in case your oven is like mine and is hotter one side).
8. Let cookies rest on the baking sheet for 5-10 minutes before transferring to a wire rack. They’re kind of fragile right out of the oven, so they need a minute to set up.

Recipe Tips & Notes

• Measure the ingredients carefully, particularly the four (fluff, spoon, level). Too much flour can make the dough dry and the cookies thick and cakey. Overdoing the mix-ins (especially candies) can cause the cookies to puff up, but super thick, and spread unevenly (or, worse case scenario, not spread at all).
• This dough is wet and sticky, so don’t panic (that’s what we’re going for). Oatmeal cookie doughs have a different and (very) soft texture. This definitely isn’t a dough you want to handle, it would be a mess (so I always use a cookie scoop, haha).
• Don’t overmix the cookie dough. Once you add the dry ingredients, mix just until combined. Overworking the dough can make the cookies tough.
• Take the cookies out when the centers are puffed up, but still look soft. They’ll finish setting up (and the tops will flatten) on the baking sheet as they cool. Underbaking helps keep the centers nice and chewy.
• Swap chocolate chips for butterscotch chips, or add a handful of finely chopped pretzels for a salty crunch. You could even ramp up the peanut butter and substitute half the chocolate chip for peanut butter chips.

Storage Recommendations

Store leftover cookies in an airtight container for 3–4 days. You can freeze baked and cooled cookies for up to 3 months. Just wrap them well and freeze them in an airtight container. When you’re ready to eat them, thaw them at room temp and enjoy.

You can also freeze the pre-scooped cookie dough balls and bake from frozen, just add a minute or two to the bake time or let them come up to room temperature and then bake as directed.