Beat butter in bowl at medium speed until creamy.
Gradually add powdered sugar and salt alternately with half & half and vanilla, beating at low speed and scraping bowl often, until well mixed. Stir in corn syrup.
Chocolate Frosting: Stir in 2 to 3 squares melted and cooled unsweetened baking chocolate.
Lemon or Orange Frosting: Stir in 1 tablespoon freshly grated lemon or orange zest.
Creamy Coconut Frosting: Stir in 1 1/2 teaspoons coconut extract or flavoring.
If necessary, add half & half, one tablespoon at a time, until desired spreading consistency.