Preheat oven to 350 degrees F. Line a cupcake pan with 12 liners.
In a medium-sized bowl, whisk together flour, baking powder and salt.
In a large mixing bowl whisk the sugar and melted butter until smooth (mixture will be gritty). Whisk in eggs, then sour cream, milk and vanilla extract until combined.
Slowly add in dry ingredients and stir until completely incorporated. Batter will be thick.
Fill cupcake lines ⅔ of the way full (about ¼ cup of batter). Bake in the preheated oven for about 20 minutes or until a toothpick inserted in the center comes out clean.
Cool completely before frosting.
Vanilla Buttercream Frosting
Using a stand mixer with the whisk attachment (or a large mixing bowl and a handheld mixer), beat butter at medium speed until smooth and creamy; 2-3 minutes.
Add confectioners sugar, vanilla and milk. Turn mixer up to high speed and beat for 3 minutes. If mixture is too thick, add more milk, a teaspoon at a time. If too thin, add more confectioners sugar, a little at a time.
Frost cooled cupcakes using a spreader or a piping bag. Depending on how much frosting you use on each cupcake, there may be some leftover.
This recipe will make about a dozen cupcakes, depending on how full you fill the cups.Depending on how much frosting you use per cupcake, there may be some leftover.