3Mix crumbs with 3 tablespoons of melted butter and 3 tablespoons of sugar.
4Press crumb mixture onto bottom of 9inch springform pan(I use the bottom of a glass to press it firmly).
5Bake this for 10 minutes.
6Beat cream cheese,3/4 cup of sugar,lemon juice and zest and 1/2 teaspoon of vanilla until well blended.
7Add eggs one at a time, mixing on low after each one just until blended.
8Pour over prebaked crust.
9Bake for 55 minutes to 1 hour until middle is almost set.
10Meanwhile while that is baking, mix the sour cream with remaining vanilla and sugar until well blended.
11When middle of cake is almost set remove from oven and carefully spread the sour cream mixture over the top and put back in the oven for an additional 10 minutes. Remove from oven and run a thin bladed knife around the rim to loosen the cake. COOL FULLY before removing pan rim. Refrigerate for at least 4 hours before serving.