For the Halloween Pumpkin Cupcakes, mix the softened butter with the powdered sugar until well blended. Add food coloring until the mixture reaches the desired color.
Stir the mixture until everything is well blended and has a fine creamy consistency. Spread buttercream over cupcakes and paint Halloween pumpkin faces with sugar lettering.
Allow the Halloween pumpkin cupcakes to set a bit in the refrigerator.