Step 5) For frosting: Beat butter, corn syrup, vanilla and salt in a large mixing bowl until light and creamy. Gradually add powdered sugar and 1/3 cup milk until fluffy, adding additional milk as needed to reach desired spreading consistency. Tint with food coloring, if desired. Pipe frosting generously onto cupcakes with a pastry bag and decorative tip. Note: If spreading frosting on cakes with a knife (instead of piping), use a half recipe of the frosting.