6 oz. pkg. chocolate chips
1 c. flour
1 c. plus 3 tbsp. sugar
1/4 tsp. salt
1/4 c. butter
3 (8 oz.) pkg. cream cheese
2 tsp. vanilla
6 eggs, separated
1 c. sour cream

Melt chocolate chips and set aside. Combine 3/4 cup flour, 3 tablespoons sugar and salt. Cut in butter until particles are fine. Stir in 2 tablespoons of melted chocolate. Press into bottom of 9 inch springform pan. Bake at 400 degrees for 10 minutes. Soften cream cheese with 1 cup sugar in large bowl.

Blend 1/4 cup flour and vanilla. Add egg yolks; beat well. Blend in sour cream. Beat whites until soft peaks form. Fold into cheese mixture. Remove 1 1/2 cups of mixture, stir in remaining chocolate. Pour 1/2 of cheese mixture over baked crust. Top with spoonsful of 1/2 chocolate mixture. Cover with remaining plain mix, then with chocolate. Cut through with spatula. Place in 400 degree oven. Immediately set at 300 degrees. Bake 1 hour. Turn off oven. Let remain for 1 additional hour. Cool 2-3 hours. Chill 8 hours.