These Monster Cookies are loaded with oats, peanut butter, chocolate chips, and M&M's. Soft and chewy, they're the ultimate cookie mashup. Get the easy recipe!

I call myself a cookie monster for a reason. This recipe is a Frankenstein mashup of all the best cookies: peanut butter, oatmeal, chocolate chip, and M&M. They come together in one dough that bakes up soft and chewy. Even the real Cookie Monster would approve.

Why You’ll Love This Monster Cookies

You get four classic cookies in one batch. No need to choose between peanut butter, oatmeal, chocolate chip, and M&M.
The texture is soft and chewy thanks to the oats and peanut butter. They stay tender for days.
The ingredient list is short and you probably have most of it already. No fancy equipment needed.

Key Ingredients for the Best Monster Cookies

Old fashioned oats, Use old fashioned rolled oats, not quick oats. They give the cookies a hearty chew and keep their shape. Quick oats will make the cookies too soft and mushy.
Peanut butter, I use regular creamy peanut butter like Skippy for this recipe. Natural peanut butter can separate and make the dough too oily. Stick with the processed stuff for the best texture.
M&M’s, The colorful candies are the star. They add crunch and a pop of color. You can use any color or seasonal variety.

Kitchen Tools for Monster Cookies

Stand mixer or hand mixer, for creaming butter and sugars.
Large baking sheets, two sheets to bake in batches.
Silpat baking mats or parchment paper, prevents sticking and ensures even browning.
Wire rack, for cooling cookies completely.
Cookie scoop (2-tablespoon size), for uniform cookies.

Tips for Making Monster Cookies That Turn Out Perfect

Don’t overmix the dough once you add the dry ingredients. Overmixing develops gluten and makes cookies tough. Just mix until the flour disappears. Also, check your baking soda’s expiration date. Old baking soda won’t give the cookies enough lift. Let the cookies cool on the baking sheet for about 5 minutes before moving them. They need that time to set, especially with all the mix-ins. If you try to move them too soon, they’ll fall apart.

Expert Tips for Monster Cookies

Use a cookie scoop to get even-sized balls. Two tablespoons of dough per cookie is the sweet spot. If you want picture-perfect cookies, press a few extra chocolate chips and M&Ms into the tops right after they come out of the oven. The flake sea salt is not optional. It balances the sweetness and makes the flavors pop. Bake until the edges are just golden but the centers are still soft. They’ll continue to set on the hot sheet.

How to Get Soft Chewy Monster Cookies

The secret to soft chewy monster cookies is not overbaking them. Pull them out when the edges are set but the centers still look slightly underdone. They’ll finish cooking on the hot baking sheet. Using brown sugar adds moisture and chewiness. Also, don’t skip the oats. They absorb moisture and keep the cookies tender for days.

These cookies are already full of goodies, but you can swap things around. Try peanut butter chips or butterscotch chips instead of some of the chocolate chips. Crushed pretzels add a salty crunch. Shredded coconut gives a chewy texture. Dried cranberries or raisins work well too. For extra crunch, toss in chopped peanuts, almonds, or walnuts. Just keep the total mix-ins around the same amount so the dough holds together.

What to Serve with Monster Cookies

Serve these cookies with a cold glass of milk. They’re also great crumbled over vanilla ice cream for a quick sundae. Or sandwich two cookies with a scoop of ice cream for an easy dessert.

How to Store Monster Cookies

Store the cookies in an airtight container at room temperature. They’ll stay fresh for 3 to 5 days. To keep them soft, toss a slice of bread into the container. The bread will get hard, but the cookies will stay tender.

How to Freeze Monster Cookies

You can freeze the dough or the baked cookies. For the dough, scoop it into balls and freeze them on a baking sheet for about an hour until firm. Then transfer to a freezer bag. Bake from frozen, adding a couple of minutes to the baking time. For baked cookies, let them cool completely, then freeze in a container for up to 2 months. Defrost at room temperature or eat them frozen. I love frozen monster cookies.