8 ounces coarsely chopped unsweetened chocolate
4 ounces coarsely chopped semisweet chocolate
1 1/3 cups sugar
1/2 cup water
1 cup unsalted kosher for Passover margarine, unsalted butter or plain unsalted margarine
Preheat oven to 350 degrees. Butter a 9-inch round cake pan. Line bottom of pan with parchment paper and butter the paper.
In food processor combine chopped chocolates. Process until finely chopped. In saucepan bring sugar and 1/2 cup water to boil. Stir to dissolve sugar.
With food processor running, add boiling sugar syrup to chocolate through feed tube. Add margarine, 2 tablespoons at a time. Add eggs.
Process only until smooth. Pour chocolate mixture into prepared pan.
Place cake pan inside roasting pan. Pour enough hot water in roasting pan to reach halfway up sides of pan.
Place roasting pan on rack in center of oven. Bake for 25-30 minutes until knife inserted in center comes out with just a few specks of chocolate clinging to the tip of the knife and cake begins to pull away from edges of pan. Transfer cake pan to a wire rack. Cool for 10 minutes. Using a small, sharp knife, loosen cake from pan sides.
Cover cake surface with plastic wrap and invert onto baking sheet. Lift off pan and remove parchment. Invert a cake plate over the cake; turn plate and baking sheet so that cake is right-side up. Remove plastic wrap. Serve warm or cold.
See this and other recipes on Elisha's blog.
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