1 1/2 c. graham cracker crumbs or Zwieback
2 tbsp. butter, melted
2 tsp. sugar

Mix together and press to bottom and sides of buttered 9 inch spring-form pan. Put in refrigerator while mixing the filling.

FILLING:

2 (8 oz.) pkgs. cream cheese, room temperature
1/2 c. sugar and 2 tbsp. flour
1 c. sour cream (1 c. yogurt could be used instead of sour cream)
4 egg yolks plus 4 stiff beaten egg whites
1 tsp. vanilla

Blend sugar, flour, and cream cheese together. Add 4 egg yolks and vanilla; mix well. Add sour cream; blend thoroughly. Fold in egg whites. Pour mixture into pan lined with cracker crumbs. Bake in slow oven (325 degrees) 1 hour 10 minutes or insert knife after 1 hour - if it comes out clean, shut oven heat off and open door slightly for 10 minutes, then take out cake and cool further. Next day it is firmer.