• Preheat oven to 350 degrees.  Use parchment paper or a silpat mat to line a baking sheet. 
• Cream the butter, sugar and brown sugar in a stand mixer until light and fluffy (about 2-3 minutes). Scrape the sides of the bowl to make sure all ingredients are blended.
• Add in egg and vanilla and beat until combined.
• Add in flour, dark cocoa, Oreo crumbs, baking soda, baking powder, and salt. Mix until all combined. 
• Scoop out dough and roll into balls. Scoop out a little less than 1 TBSP dough for smaller cookies (or 1/4 cup dough for BIG cookies). Place dough balls on prepared pan (12 cookies to a pan if smaller cookies) and slightly flatten with your hand to about 3/4 – 1 inch thick.
• Bake for 8 minutes. Cool cookies cookie sheet for 10 minutes before removing to cooling rack. NOTE: If you decide to make the bigger cookies, you’ll need to bake them for 13-15 minutes.
• While cookies are cooling, make the frosting.

Birthday Cake Cream Cheese Frosting

• In stand mixer, cream butter and cream cheese for about 2-3 minutes until smooth.
• Add in the birthday cake flavoring and powdered sugar and mix on high for about 3 minutes until smooth. If the frosting is too thick, add milk a teaspoon at a time to get the consistency you are looking for. If frosting is too thin, add more powdered sugar.
• Put the frosting in a piping bag with a star tip OR you can put the frosting in a gallon size Ziploc bag and cut off one corner of the bag. Use the frosting bag to pipe frosting in a spiral on top of the cooled cookies. Sprinkle each cookie with sprinkles and crushed oreos