- 1 1/2 cups sugar, divided
- 1/2 cup water
- 8 ounces unsweetened chocolate, finely chopped
- 4 ounces semisweet chocolate, finely chopped
- 2 sticks unsalted butter, at room temperature
- 5 large eggs, beaten
- Equipment: a 9-inch springform pan; a large (18-inch) roll of heavy-duty foil
- Accompaniment: whipped cream (optional)
- Preheat oven to 300&Deg;F with rack in middle. Wrap outside of cake pan in plastic wrap, then wrap tightly in a layer of foil.
- Lightly butter pan, then dust with sugar, knocking out excess.
- Heat 1 cup sugar with 1/2 cup water in a small saucepan, stirring, until sugar is dissolved. Remove from heat and cool.
- Melt chocolates in a large bowl set over a saucepan of barely simmering water (do not let bowl touch water), stirring occasionally, until melted. Stir together butter (2 sticks) and remaining 1/2 cup sugar in another bowl until combined. Stir butter mixture into melted chocolate. Then stir in sugar syrup. Gently stir in eggs (avoid making bubbles) until combined. 3Transfer to pan and bake in a hot water bath until center is almost set (it should barely wobble), about 45 to 50 minutes.
- Cool completely on a rack. Chill, covered, at least 8 hours. Run a thin knife along side of pan, remove side, and serve slightly chilled or at room temperature.