Preheat the Oven and Prepare the Cake Pans - Preheat the oven to 350 degrees Fahrenheit. Butter and flour the pans, then line the bottoms with wax or parchment paper.
Sift the Dry Ingredients - Using a sifter, sift the all-purpose flour, salt, and baking powder into a medium bowl. Set the dry ingredients aside.
Beat the Butter and Sugar - With an electric mixer, beat the butter for three minutes at medium-high speed. Next, add the sugar and beat for an additional three minutes.
Add the Eggs - Add the eggs into the batter, one at a time. Beat until incorporated before adding the next egg.
Add the Dry Mixture and Milk - Add the flour mixture in one cup at a time. Alternate adding a bit of the milk after each addition. Add in the vanilla extract and mix well.
Bake the Cake - Pour the cake batter into the prepared pans. Bake the cakes for 25-30 minutes or until a toothpick inserted into the middle comes out clean. To fully cool let the cakes on a wire rack.
Make the Frosting - Beat the butter with an electric mixer on medium speed in a large bowl, until light and fluffy. Add the vanilla and mix well. Gradually beat in the confectioners’ sugar, beating well after each addition, scraping down the sides of the bowl with a rubber spatula as needed.
Add in the milk and beat until the frosting is smooth and fluffy. If the frosting is too thick, add more milk until it reaches the proper consistency.
Decorate the Cake - Once the cakes are fully cool, level the tops. Between each layer of the cake add a layer of frosting. Use the remaining frosting to decorate the sides and top of the cake.