Unsweetened or bitter chocolate is made by crushing roasted cacao beans, also called cocoa beans, and releasing the liquor, which is poured into molds for hardening. It contains no sugar and has a sharp, unpleasant taste. To use it as a dip for fruit or baked goods, as a hard shell topping for ice cream, or as a glaze, you must mix in a sweetener. You can also sweeten bitter chocolate to use as a substitute in recipes that call for semisweet chocolate. Once melted and sweetened, the chocolate can be used immediately or hardened and stored for future use.
Double Boiler Method
Fill the bottom half of the double boiler with 1 or 2 inches of water, and place on a stove burner. Bring water to a boil, then reduce heat to low, or just enough to keep the water hot but not boiling.
Measure the amount of chocolate needed, and chop or grate it. Measure the sugar using a ratio of 2 tablespoons for every 1 ounce of chocolate. Place sugar in a small bowl and set aside.
Transfer the chocolate to the top section of the double boiler and place that over the bottom section. Leave the cover off and stir the chocolate frequently with a wooden spoon as it melts.
Add the sugar in small amounts, using more or less than the standard ratio according to your taste. Stir after each addition until the sugar completely melts and no longer feels gritty when you press the spoon to the side of the pan.
Turn off the burner and carefully remove the top pan from the double boiler. Proceed with your recipe or pour the melted chocolate into a bowl to cool.
Measure the chocolate and the sugar separately. Transfer the chopped or grated chocolate to a microwave-safe bowl and place it in the microwave. Set the oven to medium power and microwave the chocolate, uncovered, for 60 to 90 seconds.
Remove the bowl from the microwave and stir. Add the sugar and stir well to combine. Microwave for another 30 seconds. Remove the bowl and stir until all the chocolate pieces are completely melted and the sugar no longer feels gritty against the side of the bowl.
Use the melted sweetened chocolate immediately or pour it into a separate container and refrigerate for future use.
You can buy unsweetened chocolate in several forms, including solid bars, bars divided into 1-ounce blocks, or chips. If using divided bars, simply break off the amount you need and store the rest. If using a solid bar, weigh the desired amount on a kitchen scale, or break the bar into sections based on its total weight. (For example, a 4-ounce bar will break into four 1-ounce sections if cut evenly.)
You can also melt and sweeten the entire bar using a ratio of sugar equivalent to its total weight.
If you don't own a double boiler, place a metal or glass bowl over a saucepan containing hot water. This is a little less stable than a standard double boiler, so be sure to hold the bowl with an oven mitt or pot holder while stirring the chocolate.
Use a sharp knife to chop solid chocolate, and let the knife do the work without forcing it. If you still can't cut through a solid block, let the chocolate come to room temperature or shave it from the ends.