Add brown sugar, cocoa powder, vanilla extract, and water to a small saucepan over medium heat. Stir to combine.
1 cup brown sugar, ¼ cup cocoa powder, 1 teaspoon vanilla extract, ⅓ cup water
Cook, stirring constantly, until mixture thickens and boils. Boil and continue stirring for 1 minute.
Remove from heat and stir in butter. Serve warm over your favorite pancakes, waffles, crepes, or French toast.
2 tablespoons salted butter