# List of Ingredients:
→ Sponge Cake
01 - 2 3/4 cups all-purpose flour
02 - 1 1/2 cups granulated sugar
03 - 2 1/2 teaspoons baking powder
04 - 1/2 teaspoon salt
05 - 1 cup unsalted butter, softened
06 - 4 large eggs
07 - 1 cup whole milk
08 - 2 teaspoons vanilla extract
09 - Food coloring gels (red, yellow, green, blue, purple)
→ Buttercream Frosting
10 - 1 1/2 cups unsalted butter, softened
11 - 4 cups powdered sugar
12 - 3 to 4 tablespoons milk
13 - 2 teaspoons vanilla extract
14 - Pinch of salt
# Step-by-Step Directions:
01 - Preheat oven to 350°F. Grease and line five 8 x 8 inch square baking pans or plan to bake in batches if limited on pans.
02 - In a large bowl, beat the butter and granulated sugar until light and fluffy. Add eggs one at a time, beating after each addition, then incorporate vanilla extract.
03 - In a separate bowl, whisk together flour, baking powder, and salt until well blended.
04 - Alternately add the flour mixture and milk to the butter mixture, beginning and ending with flour. Mix gently until just combined; avoid overmixing.
05 - Divide batter evenly into five bowls. Tint each bowl with a different gel food coloring to achieve vibrant hues.
06 - Pour each colored batter into the prepared pans and spread evenly. Bake for 20 to 25 minutes or until a toothpick inserted in the center comes out clean.
07 - Allow the cakes to cool in their pans for 10 minutes, then remove and transfer to a wire rack to cool completely.
08 - Using a mixer, beat softened butter until creamy. Gradually add powdered sugar, vanilla extract, and salt. Continue beating until fluffy. Adjust consistency with milk as needed.
09 - Trim edges if needed and slice each colored sponge into uniform 1 1/4 inch squares.
10 - Arrange colored squares alternately on a large tray to create a patchwork pattern, bonding squares with a thin layer of buttercream between them. Build multiple layers for a quilted effect.
11 - Apply a thin, even layer of buttercream to the top and sides for a smooth finish. Optionally, pipe lines on the surface to accentuate the patchwork design.
12 - Refrigerate the assembled cake for 30 minutes to set the frosting before slicing and serving.