CRUST:

1/4 c. graham cracker crumbs
1 tbsp. sugar
2 tbsp. butter, melted
1 square unsweetened chocolate

FILLING:

3 (8 oz.) pkgs. cream cheese, softened
1 tbsp. orange rind, grated
3/4 c. light brown sugar, firmly packed
1/2 c. sugar
4 eggs
2 pts. sour cream
6 squares semi sweet chocolate, melted & cooled

Combine crumbs, sugar, butter and unsweetened chocolate. Press into bottom of lightly greased 9"x3" springform pan. Refrigerate.

Beat cheese until smooth, beating in sugars. Beat in eggs, one at a time, until fluffy. Beat in rind and sour cream. Reserve 3 cups. Beat cooled chocolate into remaining cream cheese mixture until well mixed. Spoon 1 cup plain cream cheese mixture over crust. Spoon half of chocolate mixture into 4 separate mounds over the plain cheese mixture. Repeat this procedure. Cut through batter with zig zag motion to obtain marble effect.

Bake at 350 degrees for 1 hour. Turn off oven and leave cake in oven 1 hour longer. Cool completely, on rack, before refrigerating overnight. To serve, remove from pan and decorate with orange slices and chocolate leaves if desired.