Brown the Butter: In a medium saucepan, melt the butter over medium heat. Continue cooking, stirring often, until the butter foams, then turns golden brown with a nutty aroma (this usually takes about 5–7 minutes). Remove the butter from heat and pour it into a mixing bowl to cool for 5–10 minutes. (Check my blog for a detailed guide to browning butter if you’re new to the process!)

In a medium saucepan, melt the butter over medium heat. Continue cooking, stirring often, until the butter foams, then turns golden brown with a nutty aroma (this usually takes about 5–7 minutes).

Remove the butter from heat and pour it into a mixing bowl to cool for 5–10 minutes. (Check my blog for a detailed guide to browning butter if you’re new to the process!)

Make the Dough Base: Once the butter has cooled, whisk in the brown sugar and granulated sugar until the mixture is smooth and glossy. Stir in the peanut butter, followed by the egg and vanilla extract.

Once the butter has cooled, whisk in the brown sugar and granulated sugar until the mixture is smooth and glossy.

Stir in the peanut butter, followed by the egg and vanilla extract.

Combine Dry Ingredients: In a separate bowl, whisk together the flour, oats, salt, baking powder, and cornstarch. Gradually fold the dry ingredients into the wet mixture until fully combined.

In a separate bowl, whisk together the flour, oats, salt, baking powder, and cornstarch.

Gradually fold the dry ingredients into the wet mixture until fully combined.

Add Mix-Ins: Gently stir in the mini M&Ms, chocolate chips, and sprinkles. Make sure they’re evenly distributed throughout the dough.

Gently stir in the mini M&Ms, chocolate chips, and sprinkles. Make sure they’re evenly distributed throughout the dough.

Chill the Dough: Cover the bowl and refrigerate the monster cookie dough for at least 30 minutes. This helps the flavors meld and ensures your cookies bake up thick and chewy.

Cover the bowl and refrigerate the monster cookie dough for at least 30 minutes. This helps the flavors meld and ensures your cookies bake up thick and chewy.

Bake the Monster Cookies: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper. Using a cookie scoop or spoon, drop the monster cookie dough into balls (about 2 tablespoons each) onto the prepared baking sheet, spacing them 2 inches apart. Bake for 10–12 minutes, or until the edges are lightly golden. The centers may look slightly underdone—that’s okay! They’ll set as they cool.

Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

Using a cookie scoop or spoon, drop the monster cookie dough into balls (about 2 tablespoons each) onto the prepared baking sheet, spacing them 2 inches apart.

Bake for 10–12 minutes, or until the edges are lightly golden. The centers may look slightly underdone—that’s okay! They’ll set as they cool.

Cool and Enjoy: Let the monster cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely. Serve and enjoy these chewy, colorful monster cookies with a glass of milk or your favorite drink!

Let the monster cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely.

Serve and enjoy these chewy, colorful monster cookies with a glass of milk or your favorite drink!