# What You'll Need:
→ Sponge Cake
01 - 2 ⅞ cups all-purpose flour
02 - 1 ½ cups granulated sugar
03 - 2 ½ teaspoons baking powder
04 - ½ 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 ½ cups unsalted butter, softened
11 - 4 cups powdered sugar
12 - 3 to 4 tablespoons milk
13 - 2 teaspoons vanilla extract
14 - Pinch of salt
# How-To Steps:
01 - Preheat oven to 350°F (180°C). Grease and line five 8 x 8 inch square baking pans, or prepare to bake in batches if pans are limited.
02 - In a large bowl, cream the butter and sugar until light and fluffy. Beat in the eggs one at a time, then incorporate vanilla extract.
03 - Whisk together flour, baking powder, and salt in a separate bowl.
04 - Alternately add the flour mixture and milk to the wet ingredients, beginning and ending with the flour mixture. Mix until just combined to avoid overmixing.
05 - Divide batter evenly into five bowls and tint each portion with different food coloring gels for vibrant hues.
06 - Pour each colored batter into its prepared pan and spread evenly. Bake for 20 to 25 minutes, or until a toothpick inserted comes out clean.
07 - Allow cakes to cool in pans for 10 minutes, then release onto wire racks to cool completely before further handling.
08 - Beat softened butter until creamy. Gradually add powdered sugar, vanilla extract, and salt, mixing until fluffy. Thin with milk to reach desired spreading consistency.
09 - Trim cake edges and slice each colored sponge into uniform 1¼ x 1¼ inch squares. Arrange squares in alternating colors on a large tray, adhering layers with a thin spread of buttercream to create a patchwork pattern.
10 - Build the cake by stacking patchwork layers, applying buttercream between each to secure the design and maintain even structure.
11 - Apply a thin crumb coat of buttercream over the assembled cake, smoothing sides and top. Optionally, pipe decorative lines with buttercream to accentuate the quilted appearance.
12 - Refrigerate the cake for 30 minutes to set the frosting, then slice and serve.