Properly melting chocolate is a key first step in making delicious desserts like rich brownies and elegant truffles. However, the process is not as straightforward as melting butter and can be tricky, requiring full attention.
Basically, cocoa butter and cocoa powder essentially make up chocolate. Cocoa butter melts at about body temperature (which you already knew if you've ever held an unwrapped chocolate bar in your hand). If you heat chocolate at too high a temperature over a direct flame, it seizes, separating into liquid cocoa butter and clumps of cocoa powder, or worse burn. The other danger is if even a little water comes into contact with melted chocolate, the sugar and cacao in the chocolate will immediately absorb the moisture and clump up into a grainy mess.
There are a few fundamental guidelines to successfully melting chocolate:
Water bath/Double boiler: Fill a large skillet with water, and heat to just below simmering. Place the chocolate in a heatproof bowl, such as stainless steel, and place the bowl in the water. Gently and constantly stir the chocolate while keeping the water below simmering. Be careful that the water doesn't boil or splash into the chocolate, because any moisture will cause it to seize.
Microwave oven: It’s best to melt chocolate on a low (50%) power setting in a microwave-safe bowl, to avoid scorching or burning it. The chocolate won't completely melt, but it will turn glossy and soft to the touch. Remove from the microwave and keep stirring and allow the residual heat to melt the rest of the chocolate As a rough guide, estimate about 1 minute for 1 ounce of chocolate, 3 minutes for 8 ounces of chocolate, 3.5 minutes for 1 pound of chocolate, and 4 minutes for 2 pounds. Run the microwave in 30 second-1 minute increments, stirring in between and rotating the bowl if necessary. Finish heating when most, but not all, of the chocolate is melted. Stir the chocolate continuously until it is smooth, shiny, and completely melted.