1/4 c. sugar
1/4 c. melted butter
1 c. graham cracker or vanilla wafer crumbs

Add sugar and crumbs to melted butter and press into bottom and sides of a 9 inch buttered springform pan. Bake for 7 minutes at 350 degrees.

FILLING:

1 lb. ricotta cheese
1 c. sour cream
3 eggs
3/4 c. sugar
1 tsp. vanilla
1/4 tsp. cream of tartar
1 lemon, grated rind

Cream ricotta with sour cream until smooth. Add 3 egg yolks, sugar, vanilla and grated rind of lemon. Beat for 30 seconds to 1 minute. Beat egg whites with cream of tartar, until soft peaks form. Fold egg whites into cheese mixture (DO NOT BEAT) and pour into cooled crust.

Put baking dish filled with boiling water on bottom shelf of oven. Bake 1 hour at 300 degrees. Turn off heat and leave in oven 30 minutes. Open oven door and let it cool in oven. When cool, remove sides of pan and refrigerate at least 3 hours before serving.