Preheat the oven to 350°F (175°C). Grease and flour two 9-inch round cake 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 dry ingredients. Mix until just combined.

Divide the batter evenly between the prepared cake pans.

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

Allow the cakes to cool in the pans for 10 minutes, then transfer to a cooling rack to cool completely.

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

Gradually add the powdered sugar, alternating with the heavy cream, and beat until smooth and fluffy.

Stir in the vanilla extract.

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

Spread a layer of buttercream frosting on top of the first cake layer.

Place the second cake layer on top and frost the top and sides of the cake with the remaining buttercream.

Decorate as desired and serve.