Chocolate Cheesecake II

Preheat oven to 350 degrees F ( 175 degrees C). Lightly grease a 9 inch springform pan. In a small bowl, mix together 1 1/2 cups chocolate wafer crumbs, 2 tablespoons sugar, and melted butter. Press onto the bottom and 1 1/2 inch up the sides of the prepared 9 inch springform pan. Bake at 350 degrees F (175 degrees C) for 10 minutes. Allow to cool. Reduce oven temperature to 325 degrees F (165 degrees C). To Make Filling: In a small saucepan, heat 1/4 cup whipping cream and 1/4 cup chocolate chips, stirring constantly, until chips are melted. Remove from heat. In a large mixing bowl, beat cream cheese and 1 cup of sugar until smooth. Add cocoa and beat well. Add eggs and beat on low until just blended. Stir in 1 teaspoon vanilla and reserved chocolate mixture until blended. Pour over crust. Bake at 325 degrees F (165 degrees C) for 45 to 50 minutes or until center is almost set. To Make Topping: In a small saucepan, heat 1/4 cup whipping cream and 1 teaspoon vanilla until just before boiling. Stir constantly and be careful not to boil over. Have 1 1/2 cups chocolate chips ready in a small bowl. Pour in the hot cream and stir with a spoon until smooth. Spread over baked cheesecake and refrigerate overnight.