Preheat your oven to 350°F (175°C) and grease six 6-inch round pans.
In a bowl, mix flour, baking powder, and salt.
Cream the butter and sugar until light and fluffy.
Add eggs one at a time, mixing well after each addition, then stir in vanilla.
Gradually add dry ingredients and milk, mixing until smooth.
Divide the batter into six bowls and add food coloring to each.
Pour each colored batter into the prepared pans.
Bake for 25-30 minutes or until a toothpick comes out clean.
Allow cakes to cool completely before frosting.
Frost with buttercream and serve.