There are many recipes out there that call for melted chocolate, from brownies to cakes. Melted chocolate might not sound like a tricky ingredient, but it actually can be and is a place where many would be brownie-bakers run into problems. This is because chocolate tends to hold its shape as it melts (because the cocoa butter melts and the cocoa solids don’t), so unlike butter or ice, so it is difficult to tell just from looking at a bowl of chopped up chocolate whether it has melted or not. If you pop a bowl full of chocolate chips in the microwave and turn it on, the chips will hold their shape until you stir them around. If you overcook chocolate that is already melted, it burns quickly, leaving you with gritty, unpleasant tasting chocolate that isn’t going to do your brownie recipe any favors.
Fortunately, it is not difficult to melt chocolate as long as you do it carefully. You can melt chocolate in a microwave or on top of a double boiler. It is best to chop up your chocolate a bit so that the pieces are small and uniform, which will allow them to melt quickly. The double boiler method is the old standard because it forces you to stand there and pay attention to the chocolate as it melts, as well as providing a gradual heat that won’t easily scorch your chocolate. It does result in a bit of extra cleanup, however, so I prefer to use method when I’m melting a larger quantity of chocolate.
The microwave method is much quicker, but also much easier to screw up. To microwave your chocolate, place it in a bowl and cook it on high in 20-30 second intervals, stopping to stir it well before putting the chocolate back in the microwave. The exact time it takes will vary by your microwave, but the chocolate will start to melt before long and the heat of the melted chocolate, along with the stirring actions, will help to melt the as-yet-unmelted chocolate in your bowl. You must check the chocolate frequently here because a few extra seconds can result in burned chocolate, and failing to stir the chocolate well means that the chocolate on the bottom of the bowl may burn before the rest of the chocolate has melted.
Update: If you are looking to temper your chocolate, rather than just melt it, try this tutorial!