Preheat the oven to 350°F (175°C). Grease and flour two 9-inch round baking pans.

In a mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking powder, and salt.

Gradually add the dry ingredients to the wet mixture, alternating with the milk, starting and ending with the flour mixture.

Divide the batter evenly between the prepared pans and smooth the tops.

Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cakes to cool in the pans for 10 minutes, then turn out onto wire racks to cool completely.

In a mixing bowl, beat the softened butter until creamy.

Gradually add the powdered sugar, mixing on low speed until combined.

Add the milk and vanilla extract, then beat on high speed until light and fluffy.

Once the cakes are completely cool, place one layer on a serving plate.

Spread a layer of buttercream frosting on top, then place the second layer on top.

Frost the top and sides of the cake with the remaining buttercream frosting.

Decorate as desired and serve.