One box of fudge brownie mix + the ingredients listed on the box
16 birthday cake Oreos
Vanilla frosting: store-bought or my homemade recipe below
Rainbow sprinkles
Vanilla buttercream
1 stick of salted butter
2 cups powdered sugar
2 tbsp heavy cream
1 tsp vanilla extract
Instructions
Preheat the oven to the time it says on the box, usually 325 or 350.
Spray an 8” square baking dish with baking spray and line it with parchment paper. It’ll be way easier to pull out!
Make the brownies according to the package instructions. Spread half of the batter into the base of the dish.
Top that layer with 16 Oreos, placing them 4 × 4.
Spread the rest of the batter evenly over the Oreos. If desired add rainbow sprinkles to the top of the batter. Bake according to the package instructions.
Let the brownies cool completely. For fudgier brownies, stick them in the fridge for a few hours!
If you’re using store-bought frosting, spread a layer on top of the brownies and add a generous amount of rainbow sprinkles.
To make homemade buttercream, beat the butter until smooth. Add in the powdered sugar and mix. Add in the vanilla and heavy cream and mix until smooth.
Spread evenly on top of the brownies and then add a ton of sprinkles. Cut them into rectangles or squares and serve