Ingredients:

  • 3 cups (375g) all-purpose flour
  • 2 cups (400g) granulated sugar
  • 1 tbsp (12g) baking powder
  • 1/2 tsp (3g) salt
  • 1 cup (225g) unsalted butter, softened
  • 4 large eggs (200g)
  • 1 cup (240ml) buttermilk
  • 2 tsp (10ml) vanilla extract
  • 1/2 cup (80g) rainbow sprinkles
  • 2 cups (450g) unsalted butter, softened
  • 6 cups (720g) powdered sugar, sifted
  • 3 tbsp (45ml) heavy cream
  • 2 tsp (10ml) vanilla bean paste
  • 1 pinch (1g) salt
  • 1/2 cup (60g) black sanding sugar
  • 1/2 cup (60g) gold sanding sugar
  • 2 oz (56g) melted dark chocolate

Instructions:

  1. Preheat your oven to 350°F (175°C).
  2. Grease a 9x13 inch pan with butter and line the bottom with parchment paper.
  3. Beat the softened butter and sugar together on medium-high until pale and fluffy, approximately 3 minutes.
  4. Add eggs one at a time, beating well after each, then stir in the vanilla extract.
  5. Alternately add the flour mixture (flour, baking powder, salt) and the buttermilk, starting and ending with the flour; mix on low until just combined.
  6. Gently fold in the rainbow sprinkles by hand with a spatula to avoid over-mixing.
  7. Pour the batter into the prepared pan and bake for 25 minutes.