Dunking Sauce

In a medium microwavable bowl (or in a saucepan over medium heat), melt the butter with the corn syrup and brown sugar, stirring once or twice (or constantly, if over direct heat) until the mixture comes to a boil. (An instant-read thermometer should read about 200°F/93°C.) Set it aside to cool just until warm, about 1 hour, and then set it in a warm place.