2 c. white sugar
1 1/2 sticks butter
1 c. light brown sugar
2 tbsp. white Karo syrup
3/4 c. milk
1 tsp. vanilla

Mix all ingredients at one time (except vanilla). Stir constantly until it begins to boil. Boil 5 minutes. Remove from heat. Add 1 teaspoon vanilla; beat until ready to spread.