To make homemade Cake With Buttercream keep a a medium bowl, and whisk together the flour, baking powder, and salt. In a large mixing bowl, beat the softened butter and sugar together until light and fluffy. This can take about 3-5 minutes. Divide the batter evenly between the prepared cake pans. Smooth the tops with a spatula. Bake in the preheated oven for 25-30 minutes or until a toothpick inserted into the center comes out clean. Allow the Homemade Cake With Buttercream to cool completely. In a large bowl, beat the softened butter until creamy. Gradually add the powdered sugar, milk, and vanilla extract, continuing to beat until smooth and fluffy. If desired, add food coloring for a pop of color. You can decorate the Homemade Cake With Buttercream with additional frosting, sprinkles, or other toppings as desired.