In a medium heatproof bowl, combine the butter and 3 ounces of the chocolate. Place the bowl over a saucepan filled with about 1 1/2 inches of simmering water (being sure not to let the bottom of the bowl touch the water) and stir occasionally until the chocolate and butter have melted and the mixture is smooth.☞ TESTER TIP: You can instead melt the mixture in the microwave, heating it at about 20-second intervals and stirring periodically until it is melted and smooth.