Preheat oven to 350 degrees. Cream together the butter and sugars with a hand mixer or stand mixer on medium speed for 3 minutes. Add in the peanut butter, egg and vanilla, mixing to combine after each addition. In a separate bowl, combine the baking soda and flour. Gradually add in the dry mixture to the wet mixture until thoroughly combined. Scrap down the sides as needed, add in the m&ms and oats. Mix in the m&ms and oats with a spoon so you don't break up the candies.
Line baking sheets with parchment paper or silicone mat. Using a teaspoon sized scoop or spoon, scoop out the cookies and roll into a ball. Flatten the tops of the cookies so they spread evenly, add more m&ms on top for looks if desired.
Bake for 6-7 minutes, they will not look fully done but they are. When they come out of the oven, use the back of a spoon and gently flatten out the cookies. Let sit on try for about 3 minutes then transfer to wired rack to cool completely. Serve and enjoy!
Mini Monster Cookies Recipe found on https://thissillygirlskitchen.com/mini-monster-cookies/ *All nutritional information is approximate and may not be 100% accurate. Please consult a nutritionist for more specific information.