1. Stir together 1/2 cup firmly packed dark brown sugar, 1/4 cup rum, 2 Tbsp. butter, and 1 tsp. molasses in a small saucepan.
2. Bring to a boil over medium-high heat, stirring constantly. Reduce heat to low, and simmer, stirring occasionally, 3 to 4 minutes or until brown sugar is dissolved and mixture is thickened and bubbly. Transfer to a serving dish. Serve immediately.
Note: If glaze becomes too thick to pour, return saucepan to cooktop, and whisk in 1 to 2 Tbsp. water. Cook over low heat, whisking until glaze thins and becomes a pourable consistency.