German Cheesecake

This is from Mom's recipe box. She got the recipe from the mother of one of my friends in Ramblewood. It is a light, fluffy cheesecake.

Crust:                                                                           
1 cup flour                                                              
1/4 cup sugar                                                         
1 Tbsp lemon peel                                                 
1/2 cup butter                                                        
1 slightly beaten egg yolk                                        
1/2 tsp vanilla                                                         
                                                                              
Filling:
5 eggs, yolks and whites separated
1 cup sugar, divided
3-8 oz cream cheese
1 pint sour cream
1 tsp vanilla
1 tsp orange peel
1 tsp lemon peel                                                      
1 Tbsp flour
cinnamon for dusting


Crust:
Combine flour, sugar and lemon peel. Cut in butter until mixture is crumbly. Add egg yolk and vanilla.
Blend thoroughly. Pat 1/3 of dough onto bottom of spring-form pan (sides removed). Bake 6 minutes at 400 degrees, until golden. Cool,
Butter sides of pan and attach to cooled bottom. Pat the remaining dough around sides. It will only come about half-way up. Set pan aside and prepare filling.

Filling:
Beat 5 egg whites stiff but not dry, adding 1/2 cup sugar gradually.
In separate bowl, beat cream cheese and remaining 1/2 cup sugar until creamy. Add sour cream, 5 egg yolks, vanilla, orange and lemon peels and flour. Blend well. Fold in egg whites.
Pour into pan and sprinkle all over with cinnamon.

Bake at 500 degrees for 8 minutes. Without opening the oven door, turn temp down to 250 degrees. Bake for an additional hour. Cool for 3 hours on rack. Refrigerate. Serve chilled.