Really it is. Somewhere between a chocolate chip cookie and an oatmeal peanut butter masterpiece lives this humble little monster cookie. And I say humble with the utmost affection because these cookies are kind of loud. But, I mean that in a really good way.

They’re soft and chewy, loaded with peanut butter, oats, mini chocolate chips, and of course M&Ms. I started making these years ago when I wanted a hearty cookie full of all of my favorite things. These cookies have no rules and no fancy ingredients. In fact, anything goes. They’re just the kind of cookie you can’t stop eating…straight off the cooling rack. (Ask me how I know this.)

And while monster cookies come in all shapes and sizes (with everything from raisins to rainbow sprinkles), I’m partial to this version. It’s simple, rich, and balanced, crisp edges and soft, chewy centers. Just the right mix of cozy and colorful.

Ingredient Notes

• Unsalted butter (room temperature) – Creams well with the sugars for a smooth, fluffy peanut butter cookie base. If you forget to take it out ahead of time, 10 seconds (unwrapped) in the microwave should do it.
• Granulated sugar – Adds structure and helps the edges crisp up.
• Brown sugar (light or dark) – Brings moisture and depth; it’s the key to that soft, chewy center. I like to use dark brown sugar here for a little extra richness and chew.
• Use rolled oats, not quick-cooking oats. Rolled oats hold their shape better during baking, giving the cookies structure and chew without turning to mush. Quick oats can make the dough dense and gummy.
• All-purpose flour – Spoon and level the flour accuracy; too much will make the cookies dry and very stiff (aka not good).
• Smaller mix-ins = better texture. Stick with mini M&Ms for this recipe. You can use mini or regular size chocolate chips for these cookies, 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 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 your stand mixer), cream butter, sugar, and brown sugar together with an electric mixer on medium speed for 1–2 minutes until fluffy.

3. Mix in the peanut butter, egg, and vanilla extract just until combined.
4. Add 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. Be precise with your flour and candy. 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.
• Speaking of texture. This dough is wet and sticky, so don’t panic. 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 always use a cookie scoop, haha).
• Don’t overmix. Once you add the dry ingredients, mix just until combined. Overworking the dough can make the cookies tough.
• Underbake slightly. 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.
• Customize. 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 & Freezing Recommendations

• Store cookies in an airtight container at room temp for 3–4 days.
• Freeze baked cookies for up to 3 months. Wrap them well and when you’re ready to eat them, thaw them at room temp.
• You can also freeze the dough balls and bake from frozen—just add a minute or two to the bake time.

I’ve made a lot of cookies in my life (as you know, haha), but these monster cookies are the ones I reach for when I want something cozy but a little extra. They’re peanut buttery, nostalgic, and have just the right amount of randomness—in the best possible way. If you’re looking for a cookie that’s as fun to make as it is to eat, this is the one.