Caramel Sauce for Baked Meringue Apples

Combine 1/4 cup boiling water and sugar in a medium saucepan. Cook on high until caramel forms, about 5 minutes. Remove from heat, and slowly whisk in remaining 1/2 cup water at arm's length, being careful not to splatter hot caramel. Whisk until mixture is smooth. Remove from heat, and stir in vanilla and cognac. Serve.