To make a vanilla cupcake, preheat oven to 350 degrees. Using an electric mixer, combine 2/3 cups of softened butter with 3/4 cup sugar. Stir in 3 eggs, vanilla and 1 1/2 cups self rising flour. Spoon into greased muffin tray and bake for 20 minutes. Cool and frost.
To make chocolate peanut butter cupcakes, first prepare the filling. In a large bowl, mix together at medium speed 1/2 cup of creamy peanut butter, 10 tablespoons of confectioner's sugar, 2 tablespoons of butter and 1/4 teaspoon of vanilla extract until well blended. Shape and form 24 well-rounded balls and place each one on a waxed paper lined cookie sheet.
Preheat oven to 350 degrees and line cupcake baking sheets with fluted paper liners. Using waxed paper, combine 1 teaspoon cocoa, 1 3/4 cup flour and 1/2 teaspoon of salt baking soda.
In a large bowl, mix in 1 cup of sour cream, 2 tablespoons of milk and a few drops of vanilla. Set aside.
In a large mixing bowl, beat 1 1/2 cups granulated sugar with 8 tablespoons of butter until well blended. Alternate adding in flour mixture and sour cream mixture until well combined.
Spoon batter into cupcake baking sheet and place 1 peanut butter ball in each cupcake. Bake for 25 to 28 minutes. When cooled, frost.
To make frosting mixture, combine 3 cups of confectioner's sugar, 6 tablespoons of butter, 1 teaspoon of vanilla extract and 3 tablespoons of milk. Blend well.