Bring 1 inch of water to a boil in a small saucepan. Remove from the heat and place the chocolate, butter, and corn syrup in a heat-proof bowl just large enough to fit snugly over the pot of water.
Place the bowl over the pot of hot water, and stir until the chocolate and butter have melted.
Allow the mixture to cool down until it is barely warm.
Glaze can be used to dip donuts, cookies, muffins, and to cover cakes. Place glazed baked goods into the refrigerator to firm up.