3/4 pound bittersweet or semisweet couverture chocolate
Chocolate-tempering thermometer (we like the CDN TCH130; $10, amazon.com)
1. Chop chocolate. Reserve 1/4 pound; place the rest in a heatproof bowl.
2. Bring 2 inches of water to a simmer in a saucepan; turn off heat. Rest the bowl on the pan’s rim, stirring the chocolate gently with a rubber spatula as it melts. When it reaches 118 degrees to 120 degrees, remove the bowl. Cover saucepan to keep water warm.
3. Add the reserved chocolate; stir constantly until the mixture cools to 82 degrees. Remove any unmelted pieces of chocolate with spatula. Line bottom of bowl with a kitchen towel and place back over the simmering water, stirring constantly until it reaches 88 degrees to 90 degrees. (The towel will help ensure the chocolate does not climb above 90 degrees, which would caise to "bloom" when set.) Use immediately, stirring frequently while using to maintain temper and prevent streaking once chocolate hardens. If tempered chocolate thickens too much during use, place over simmering water again, stirring, 2 to 3 seconds.
1. Use a high-quality couverture chocolate, such as Valrhona or Callebaut. Do not use chocolate chips or morsels used in cookies and other baked goods.
2. To temper milk chocolate, melt initially to 112 degrees to 114 degrees, then let cool to 80 degrees to 82 degrees, then rewarm to 84 degrees to 86 degrees. To temper white chocolate, melt initially to 112 degrees to 114 degrees, then let cool to 78 degrees to 80 degrees, then rewarm to 82 degrees to 84 degrees.
3. Never use a wooden spoon when tempering: Wood retains odor and moisture, which can compromise flavor and cause the chocolate to develop a white coating, or "bloom." Always use a rubber spatula instead.
4. Do not let any water get into the chocolate; this will also compromise the chocolate and cause it to bloom.
5. Be sure to use a chocolate-tempering thermometer -- it's designed to register precise temperature and ensure properly tempered chocolate. Regular candy thermometers are not sensitive enough to register precise readings for lower temperatures, as required in tempering.
6. Do not let the thermometer touch the bottom of the bowl, or your reading will be inaccurate.