Weigh out the ingredients
You'll need flour, baking soda, baking powder, cornstarch, salt, brown sugar, sugar, peanut butter, butter, egg, egg yolk, oats, m&ms, and chocolate chips.
Make the cookie dough
Make the cookie dough, then gently fold in the oats, m&ms, and chocolate chips. Chill for one hour.
Portion the cookie dough with a cookie scoop, then freeze for 15 minutes.
Portion the cookie dough
Bake the cookies for about 12 minutes. Allow the cookies to cool completely on the baking sheet.
Enjoy these soft & thick monster cookies with a glass of milk!