The method of melting chocolate & then cooling it to room temperature is called tempering.

cooking time: 10 mins
preparation time: 5 mins
makes 2 cups

Ingredients
250 gms chocolate (dark, milk or white)

Method
1) Chop the chocolate into small even-sized pieces & put in a bowl.
2) Place the bowl on top of a double boiler, taking care to see that the base of the bowl is not in contact with the water in the double boiler.
3) Once the chocolate starts melting, stir continuously till the chocolate melts completely & resembles a smooth sauce.(about 42 ^o C/ 108 ^o F)
4) Immediately remove from the double boiler & pour onto a clean, dry marble surface or our kitchen platform.
5) Cool the chocolate to room temperature using a palette knife by using the flat side in an up & down motion, so that the chocolate cools evenly & no lumps remain.(appx 26 ^o C/ 80 ^o F)
6) At room temperature, the chocolate will neither be warm not cold. To test the temperature of the chocolate, touch it with the help of your palette knife or dough cutter.
8) Use this melted chocolate immediately as required in the recipe.

GOLDEN RULES OF CHOCOLATE TEMPERING
Do not ovrheat chocolate since when over cooked, the chocolate turns from a glossing, liquid mass to a dull, course textured mass in which case, the chocolate will have to be discarded.
 The chcoloate will thicken while you are working at it. If this happens, melt it again on the double boiler, taking care to see that it does not burn.

recipe source Tarla Dalal