How to Frost a Layer Cake
Step 1: Place one cake layer on a plate or cake stand. Gently slide pieces of parchment paper under edges of cake. Spoon about 1/2 cup buttercream frosting onto the bottom layer; push to edge leaving a 1/2-inch border. A swiveling cheese board is a great substitute if you don’t have a revolving cake stand.
If you use all-purpose flour instead of cake flour, reduce the amount of flour called for by 2 Tbsp. per cup. Or make your own version of cake flour by whisking together 3/4 cup all-purpose flour plus 2 Tbsp cornstarch for each cup of cake flour.