This recipe was created to accompany Fallen Chocolate Squares À La Mode with Butterscotch Sauce. Can be prepared in 45 minutes or less, but requires additional unattended time.

Ingredients

　　1 cup sugar

　　1/4 cup light corn syrup

　　3 tablespoons water

　　1/2 stick (1/4 cup) unsalted butter, cut into 4 pieces

　　1 teaspoon cider vinegar

　　1/2 cup heavy cream

　　2 teaspoons vanilla

　　In a 1 1/2-quart heavy saucepan bring sugar, corn syrup, and water to a boil over moderate heat, stirring until sugar is dissolved. Boil mixture, without stirring but swirling pan occasionally, until a golden caramel. Remove pan from heat and add butter, vinegar, and a pinch salt, swirling pan until butter is melted. Add cream and vanilla and simmer, stirring, 1 minute (sauce will be a golden brown). Cool sauce to room temperature (sauce will thicken as it cools). Sauce keeps, covered and chilled, 3 weeks. Serve sauce warm or at room temperature.