Chocolate Ganache

Directions

1. 1
   Put the chopped chocolate in a medium heatproof bowl.
2. 2
   Bring the cream to a boil (you can do this in a microwave oven) and pour half of it over the chocolate. Wait for 30 seconds and then, using a whisk or a heatproof spatula, gently stir the chocolate and cream together in small circles, starting in the center of the bowl and working your way out in ever-widening concentric circles. Pour in the rest of the cream and repeat the circular mixing. When the ganache is smooth and shiny, drop in the butter pieces one by one, mixing until each piece is blended before adding the next. Be gentle -- you don't want to beat the ganache, nor do you want to aerate it.
3. 3
   If you're using the ganache as a filling for a tart or glaze, use it immediately. If you're using it to fill and frost a cake, you'll have to wait for it to thicken. You can leave it on the counter, stirring occasionally (it thickens slowly), or you can set the bowl into a larger bowl filled with ice cubes and water, in which case, stir often and stay close -- it thickens lightning-fast. Alternatively, you can put it in the refrigerator, checking on it and stirring frequently. If the ganache has firmed too much, you can always reheat it (see below).
4. 4
   Storing: Tightly covered, the ganache will keep in the refrigerator for up to 5 days or in the freezer for up to 2 months. Let it come to room temperature before using. You can also bring the ganache to temperature in a microwave oven -- heat in very short spurts and don't forget to stir -- or you can put the bowl over a saucepan of simmering water and stir until you get the consistency you want. However you warm the ganache, be gentle -- too much heat, and it may separate.