Put the chocolates in a medium heatproof bowl. Bring a saucepan filled with 1 inch or so of water to a very slow simmer; set the bowl over, but not touching, the water. Stir the chocolate occasionally until melted and smooth. (Alternatively, put the chocolate in a medium microwave-safe bowl. Melt at 50 percent power in the microwave until soft, about 1 minute. Stir, and continue heat until completely melted, about 1 to 2 minutes more.)