How To Melt Chocolate

* Double Boiler Method
o This is probably the most traditional method of melting chocolate. If you do not have a double boiler, place a small heatproof bowl over a saucepan. Make sure the bowl fits snugly so no water or steam can splash into it. Do not allow the water in the bottom of the double boiler or saucepan to come to a boil.
o Place the broken or chopped chocolate in the double boiler top or bowl and place over double boiler bottom or saucepan. Lower the heat as much as possible, or turn it off completely, and allow the chocolate to melt slowly, stirring frequently.

* Direct Heat Method
o When a recipe directs melting chocolate with a liquid such as milk, cream or even butter, it can be done over direct heat in a saucepan. Choose a heavy-bottomed saucepan and melt the chocolate and liquid over low heat, stirring frequently, until chocolate is melted and smooth. Remove from heat immediately. This method is also used for making sauces, icings, and some sweets.
o Chocolate can also be melted in a very low oven (about 110C/225F). Put the chocolate in an ovenproof bowl and place in the oven for a few minutes. Remove the chocolate before it is completely melted and stir until smooth.

* Microwave Method
o The microwave is ideal for melting chocolate quickly and easily, but remember to check it during the cooking time. Place chopped or broken chocolate in a microwave-safe bowl and microwave on MEDIUM power (50%) for about 2 minutes for 115g dark, bittersweet, or semi-sweet chocolate. Milk and white chocolate should be melted on LOW power (30%) for about 2 minutes for 115g of chocolate.
o These times are for a 650-700W oven and are approximate times as both chocolate and microwave ovens vary, so check the chocolate about halfway through cooking time. The chocolate does not change shape, but begins to look shiny and must then be stirred until completely melted and smooth.

(Source – Irresistible Chocolate by Elizabeth Wolf–Cohen)