Mix together sugar, corn syrup, and water in a medium saucepan. Place over medium - low heat and stir constantly until the icing reaches 100º F. Remove from heat, stir in vanilla, and pour over prepared cakes or cookies.
Notes
Leftover icing may be stored in an airtight container in the refrigerator and reheated to 100º F for using. You may also use this fondant icing to dip in cookies, petit fours, etc.Makes about 1 1/4 cups. Nutrition information is for 2 tablespoons.