Ingredients:

  • 3 and 3/4 cups (443g) sifted all-purpose flour, spooned & leveled
  • 2 teaspoons baking powder (10g)
  • 3/4 teaspoon baking soda (3.75g)
  • 1 teaspoon salt (6g)
  • 1 and 1/2 cups (340g) unsalted butter, softened to room temperature
  • 2 cups (400g) granulated sugar
  • 5 large eggs, at room temperature
  • 3 teaspoons pure vanilla extract (15ml)
  • 1 and 3/4 cups (420ml) buttermilk, at room temperature
  • 1/3 cup (50g) rainbow sprinkles (plus more for garnish)
  • 2-3 drops teal gel food coloring (or any color)
  • 1 and 3/4 cups (396g) unsalted butter, softened to room temperature
  • 7 cups (840g) confectioners' sugar
  • 6 Tablespoons (90ml) heavy cream
  • 1 teaspoon pure vanilla extract (5ml)
  • 1/4 teaspoon salt (1.5g)

Instructions:

  1. Preheat oven to 350°F (177°C). Grease and flour four 9-inch cake pans, then line with parchment paper rounds and grease the parchment again.
  2. Whisk together flour, baking powder, baking soda, and salt in a large bowl. Set aside.
  3. In a separate bowl, beat butter until creamy. Gradually add sugar and beat until light and fluffy.
  4. Beat in eggs one at a time, then stir in vanilla extract.
  5. Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk. Mix until just combined – do not overmix!
  6. Divide batter in half. Stir sprinkles into one half and food coloring into the other.
  7. Pour batters into prepared pans, spreading evenly. Bake until a toothpick inserted into the center comes out clean.
  8. Let cakes cool in pans for 10 minutes, then invert onto a wire rack to cool completely. Crucial step!
  9. Using a 6-inch and then a 3-inch round cookie cutter, cut circles out of each cooled cake, creating rings.
  10. Beat butter until creamy. Gradually add confectioners' sugar, heavy cream, vanilla, and salt. Beat until light and fluffy. Adjust consistency as needed with more sugar or cream.
  11. Place a coloured cake ring on a serving plate. Fill with a sprinkle cake ring, then a coloured cake circle. Repeat with next layer: sprinkle ring filled with a coloured ring, then sprinkle circle. Repeat with layers until use all the layers.
  12. Frost the entire cake with vanilla buttercream.
  13. Refrigerate for at least 1 hour before slicing and serving.