1 1/2 c. chocolate wafer crumbs (about 30 cookies)
3 tbsp. butter, melted
1/2 c. semi-sweet chocolate pieces
4 (8 oz.) pkgs. cream cheese, softened
1 1/4 c. sugar
3 tbsp. cornstarch
1/4 tsp. salt
5 lg. eggs
1 (8 oz.) sour cream
2 tsp. vanilla
1 1/2 c. heavy or whipping cream
12 (1 oz.) sq. semi-sweet chocolate
8 oz. white chocolate or 1 1/2 pkgs. (6 oz.) white baking bar squares

Preheat oven to 350 degrees. Grease 9x13 inch springform pan.

Mix cookie crumbs and butter and press firmly into bottom of springform pan for crust. Bake 12-15 minutes - remove from oven and sprinkle with chocolate chips. Let stand a few minutes until soft and spreadable. Place in refrigerator while making filling.

Beat cream cheese until light and fluffy. Add sugar, cornstarch, and salt and blend well on medium speed. On low speed beat in eggs, sour cream and vanilla and 1 cup heavy cream. Divide batter into 2 measuring cups or something with a spout.

Melt over low heat 8 ounce chocolate squares and stir into one measuring cup. In another saucepan over low heat, melt white chocolate and stir into other measuring cup.

To create zebra or bullseye pattern pour 1/2 ounce dark batter into springform pan. Holding white batter about 2 feet above pan, pour 1/2 directly into center of dark batter. (This forces dark batter to sides and creates rings.) Repeat 3 times decreasing in amounts from 2 feet above pan and end with white batter.

Bake at 350 degrees for 30 minutes. Then reduce heat to 225 degrees and bake for 1 hour and 45 minutes or until center is set. Turn off oven, but let cheesecake remain in oven for 1 hour. Remove from oven. Run knife around edge of cheesecake to loosen from pan. Cool on wire rack. Refrigerate 6 hours or until well chilled. About one hour before serving prepare chocolate glaze.

CHOCOLATE GLAZE:

In small pan over medium heat, heat remaining 1/2 cup heavy cream until small bubbles form around edges. Stir in remaining 4 squares semi-sweet chocolate until melted and smooth. Cool glaze for 10 minutes. Remove cheesecake from pan. Spread glaze over top and sides. Refrigerate 30-45 minutes until set.