In the '80s and early '90s, chocolate cheesecake was at the top of our list. The simple ingredients in this rich, dense version let a good boutique chocolate shine.
02Stir chopped chocolate in metal bowl set over saucepan of simmering water until melted and smooth. Remove bowl from over water; cool chocolate until lukewarm but still pourable. Blend cream cheese, sugar, and cocoa powder in processor until smooth. Blend in eggs 1 at a time. Mix in lukewarm chocolate. Pour filling over crust; smooth top. Bake until center is just set and just appears dry, about 1 hour. Cool 5 minutes. Run knife around sides of cake to loosen. Chill overnight.
03Stir cream, 6 ounces chocolate, and sugar in heavy medium saucepan over low heat until smooth. Cool slightly. Pour over center of cheesecake, spreading to within 1/2 inch of edge and filling any cracks. Chill until topping is set, about 1 hour. Do ahead: Can be made 3 days ahead. Cover with foil and keep refrigerated.
04Release pan sides. Transfer cheesecake to platter. Top with chocolate curls. Let stand 2 hours at room temperature before serving.