* This 6 oz of chocolate chips should be melted and cooled slightly.
1. Combine crumbs and butter; press onto the bottom of a 23 cm springform pan.
2. Combine 24 oz cream cheese and sugar, mixing on medium speed until well blended. Blend in sour cream and vanilla. Pour over crust.
3. Combine remaining 8 oz cream cheese and melted chocolate; mix well. Add red raspberry preserves; mix well. Drop rounded measuring tablespoons full over the plain cheese mixture; do not swirl.
4. Bake at 160ºC for 1 hour 25 minutes. Loosen cake from rim of pan; cool before removing from pan. Melt chocolate pieces and whipped cream over low heat stirring until smooth. Spread over cheesecake. Chill and garnish with additional whipped cream and raspberries.