Preheat your oven to 350°F (175°C).
Grease and flour six 6-inch round cake pans.
In a bowl, whisk together flour, baking powder, and salt.
In a large bowl, cream the butter and sugar until light and fluffy.
Add eggs one at a time, mixing well after each addition.
Stir in vanilla extract.
Gradually add the dry ingredients to the butter mixture, alternating with milk.
Divide the batter evenly into six bowls.
Add a different color of food coloring to each bowl and mix thoroughly.
Pour each colored batter into prepared pans and bake for 25-30 minutes.
Allow cakes to cool for 10 minutes before transferring to wire racks.
Once cool, frost with your favorite frosting and stack layers.