To make an easy bread pudding sauce, combine 3/4 cup brown sugar, 1/3 cup water, 1/2 cup butter and a 1/4 cup dark rum in a small saucepan. Bring the mixture to a boil over medium-high heat, then reduce the heat, and boil gently for 10 minutes or until the sauce is thick enough to coat the back of a spoon. The sauce can be served warm or at room temperature.
Although rum sauce is traditional, many people prefer vanilla or caramel sauce for bread pudding. To make a vanilla sauce, mix together 1/2 cup white sugar, 3 tablespoons light brown sugar, 1 tablespoon flour and a dash of ground nutmeg in a heavy saucepan. Combine 1 large egg, 2 tablespoons butter and 1 1/4 cups whipping cream and add them to the dry ingredients. Whisk constantly while cooking over medium heat until the mixture is thickened. Remove the sauce from heat and whisk in 1 tablespoon vanilla extract.
To make a caramel sauce, mix together 1/2 cup butter and 1 cup brown sugar in a heavy saucepan over medium heat. When the mixture comes to a boil, remove from heat, and whisk in 1/4 teaspoon salt, 1 teaspoon vanilla and 1/2 cup evaporated milk. This sauce can be used immediately or reheated in the microwave.