• Step 1: Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
• Step 2: In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
• Step 3: In a large bowl, cream the softened butter and sugar together until light and fluffy, about 2-3 minutes. Beat in the eggs one at a time, then stir in the vanilla extract.
• Step 4: Alternate adding the flour mixture and milk to the butter mixture, mixing just until combined after each addition. Be careful not to overmix.
• Step 5: Divide the batter evenly into three separate bowls. Color one portion red and one portion blue with the food coloring, leaving the third portion plain white.
• Step 6: Carefully spoon the colored batters into the prepared cake pans, creating a layered effect. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
• Step 7: Allow the cakes to cool in the pans for 10 minutes, then transfer them to a wire rack to cool completely before frosting.