While apples are cooling, prepare caramel sauce. In a medium saucepan, melt 4 tablespoons of butter. Once melted, add the flour and cornstarch to make a paste. Add 1/4 cup water, 1/2 cup brown sugar and 1/4 cup of sugar. Bring to a boil, stirring constantly. Once the mixture reaches a boil, lower the heat and simmer for three minutes. Remove from heat and add 1 teaspoon vanilla.