Ingredients:

  • 2 1/4 cups (280g) all-purpose flour
  • 1 1/2 cups (300g) granulated sugar
  • 3 tsp (12g) baking powder
  • 1/2 tsp (3g) salt
  • 3/4 cup (170g) unsalted butter, softened
  • 1 cup (240ml) whole milk, room temperature
  • 1 tbsp (12ml) pure vanilla extract
  • 2 large eggs, room temperature
  • 1 cup (225g) unsalted butter, softened
  • 3.5 cups (420g) powdered sugar, sifted
  • 2 tbsp (30ml) heavy cream
  • 1 tsp (5ml) vanilla extract
  • 1 pinch (1g) salt
  • 2 cups (350g) rainbow nonpareil sprinkles

Instructions:

  1. Preheat oven to 350°F (175°C) and line a 9x13 inch baking pan with parchment paper.
  2. Cream the softened butter and granulated sugar together until pale and fluffy. Beat in eggs one at a time, then stir in the vanilla extract.
  3. Alternately add the dry ingredients (flour, baking powder, salt) and the room temperature milk to the butter mixture, mixing until just combined.
  4. Spread the batter evenly in the prepared pan and bake for 25-30 minutes until a toothpick inserted in the center comes out clean.
  5. Allow the cake to cool completely, then chill in the refrigerator for 30 minutes to ensure clean cuts.
  6. Use a 3-inch circular biscuit cutter to press straight down into the sheet cake to create 8 uniform rounds.
  7. Whip the buttercream butter until smooth. Gradually add powdered sugar, heavy cream, vanilla, and salt until the frosting is stiff but spreadable.
  8. Apply a generous layer of buttercream to the top and sides of each cake round.
  9. Immediately press each frosted cake round into the rainbow nonpareil sprinkles until the entire exterior is completely and densely coated.