Mix cream cheese, 3/4 cup sugar, and egg yolks. Beat with electric mixer. Beat egg whites until stiff, but not dry. Fold into cream cheese mixture. Butter 4 muffin pans; coat with graham cracker crumbs. Preheat oven to 350 degress. Fill muffin pans 3/4 full. Bake 15 minutes. Remove from oven and cool in pans. Raise temperature to 400 degrees. As the cakes cook, they tend to sink at bit in the middle.
Mix the sour cream, 3 tablespoons sugar, vanilla and place about 1 teaspoon of the mixture in each muffin tin cup. Top with preserves. Bake for 5 minutes. Let cook in pan for 5 minutes. Loosen edges and finish cooling on rack. Freezes well.
Makes 60 mini cheesecakes.