Prepare graham cracker crust.

1 1/2 c. graham cracker crumbs
1/4 c. sugar
1 1/2 lbs. cream cheese
3/4 c. sugar
Yolk of 4 eggs (reserve whites)
1 tsp. vanilla

Pour graham cracker crumbs and sugar into springform pan. Preheat oven to 275 degrees. Combine cream cheese, 3/4 cup sugar, 4 egg yolks and vanilla. Mix together until thoroughly blended.

In separate bowl, beat egg whites until soft peaks form. Slowly add 1/4 cup granulated sugar. Continue until whites form solid peaks. Gently fold egg white mixture into cheese batters. Pour into springform pan and bake at 275 degrees for 1 hour and 10 to 20 minutes until hairline cracks develop on top. Turn off oven and allow cake to cool in oven until room temperature about 1 to 1 1/2 hours.

TOPPING: Turn oven to 300 degrees and mix:

1 c. sour cream
3 tbsp. sugar

Mix and spread over top of cooled cake. Bake for 10 minutes. Remove and allow to cool to room temperature, then refrigerate overnight.