Instructions: **Begin preparing this two days before you plan to serve

Line strainer with three layers of cheesecloth. Set over large bowl. Add yogurt. Fold cheesecloth over yogurt. Place in refrigerator. Let yogurt drain overnight. Discard liquid.

Preheat oven to 350 . Mix graham cracker crumbs, vanilla extract and cinnamon in small bowl. Mix in margarine. Press mixture onto bottom and 1 inch up sides of 9-inch diameter springform pan. Bake crust 10 minutes.

Cool. Maintain oven temperature.

Boil orange juice and grated peels in small saucepan until reduced to 1/4 cup, about 9 minutes. Cool.

Mix drained yogurt, reduced orange juice mixture, sour cream, sugar, flour and yolks in medium bowl to blend. Beat egg whites in another medium bowl until stiff but not dry. Fold egg whites into sour cream mixture in 2 additions.

Pour filing into crust. Bake cheesecake until filling sets, about 30 minutes. Remove cake from oven. Cool on rack. Refrigerate cheesecake overnight.

Using small knife, cut around sides of cake to loosen. Release pan sides.

Transfer cake to platter.

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