Preparation / Directions:
Place chocolate in a double boiler and heat over hot water until it melts.
Stir to blend and let cool to room temperature.
With an electric mixer, blend cheese and sugar until smooth. Mix in eggs, vanilla, and sour cream. Stir in melted chocolate. NOTE: it is important to have the cheesecake ingredients and the melted chocolate close to the same temperature when they are combined so that they blend together smoothly. Pour into a greased 9-inch springform pan. Bake in the middle of a preheated 325F oven for 25 minutes or until just barely set. Turn off the oven, leave the door ajar, and let cool in oven for 1 hour longer. Chill.
Just before serving, dust cocoa through a sieve making a ring around the cheesecake.
Prepare raspberry sauce: Reserve 1/2 cup raspberries for garnish. In a blender, puree the remaining berries and push through a sieve. Stir in sugar to taste. To serve, spoon raspberry sauce on to desert plates. Remove pan sides of cheesecake and cut into wedges. Place on raspberry sauce and garnish with berries.