Preheat your oven to 350°F (175°C).
Grease and flour two 9-inch round cake pans.
In a large bowl, cream together the butter and sugar until light and fluffy.
Add eggs one at a time, mixing well after each addition.
Stir in the milk and vanilla extract.
In a separate bowl, combine flour and baking powder.
Gradually add dry ingredients to the wet mixture and mix until smooth.
Divide the batter into two bowls, tint one with blue and the other with pink food coloring.
Pour the blue batter into one pan and the pink into the other.
Bake for 30-35 minutes, or until a toothpick inserted comes out clean.
Let the cakes cool before frosting.