Place 1 1/2 cups of the chocolate in a heat-proof glass bowl and put it in the microwave on high for 30 seconds. Stir the chocolate with a rubber spatula, return it to the microwave for another 30 seconds, then stir again. Continue to heat and stir in 30 second intervals until the chocolate is just melted. Immediately stir in the remaining 1/2 cup of chocolate and allow it to sit at room temperature, stirring often, until it's completely smooth and glossy. (If you need to heat it a little more, place it in the microwave for another 10 seconds.)