# 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
# Step-by-Step Guide:
01 - Preheat the oven to 350°F. Grease and line five 8x8 inch square baking pans, or plan to bake in batches if pans are limited.
02 - In a large bowl, use an electric mixer to cream the butter and sugar until light and fluffy. Beat in eggs one at a time, then add the vanilla extract.
03 - In a separate bowl, whisk together the flour, baking powder, and salt.
04 - Alternate adding the dry mixture and milk to the creamed butter mixture, starting and ending with the dry ingredients. Mix until just combined to avoid overmixing.
05 - Divide the batter evenly into five bowls. Tint each portion with a different food coloring gel.
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 before turning out onto wire racks to cool completely.
08 - Beat the softened butter until creamy. Gradually add powdered sugar, vanilla extract, and salt, continuing to beat until fluffy. Add milk as needed to reach a spreadable consistency.
09 - Trim the edges of each colored sponge cake and cut into uniform 1¼ x 1¼ inch squares.
10 - On a large tray, arrange the colored squares in an alternating pattern to create a patchwork effect. Use a thin layer of buttercream as adhesive between squares to join them. Build layers by alternating colors for a quilted appearance.
11 - Apply a thin layer of buttercream over the top and sides of the assembled layers, smoothing the surface. Optionally, pipe buttercream lines to enhance the patchwork design.
12 - Refrigerate the finished cake for 30 minutes to set the frosting before slicing and serving.