A fun play on the monster cookie perfect for Halloween!
Line two baking sheets with parchment paper. Preheat oven to 350°. Cream together butter, brown sugar, and peanut butter with an electric mixer until light and fluffy, about 3 minutes. Add the egg and vanilla, scraping the bowl as needed. Add flour, baking powder, baking soda, cornstarch, salt, and oats. Mix until just combined. Add chips, peanuts, and chocolate candies. (I hold back some of the candies to press into the tops of the cookies) Scoop onto prepared sheets using a 1⁄4 cup ice cream scoop. Press chocolate candies and candy eyes into the dough. Bake for 13 to 15 minutes or until the edges begin to brown. Cool on the baking sheet for 5 minutes before transferring to a rack to cool completely.