Nut Crust (recipe follows)
3 3/4 c. part-skim ricotta cheese
2 whole eggs
3 egg whites
1 c. buttermilk
1/2 c. sugar
2 tsp. vanilla
2 tbsp. lime or lemon juice
Grated rind of 1 lime or 1/2 lemon
1/4 tsp. salt, optional

1. Preheat oven to slow (325 degrees). Grease 9 inch springform pan. Press Nut Crust in even layer over bottom and side of prepared pan.

2. Bake crust in preheated slow oven (325 degrees) for 10-15 minutes or until light golden. Remove springform pan to wire rack to cool. Increase oven temperature to moderate (375 degrees).

3. Combine ricotta, eggs, egg whites, buttermilk, sugar, vanilla, lime or lemon juice, grated rind and salt, if using, in electric blender or food processor. Puree until light and airy. Pour into prepared crust. Place large pan of water in bottom of oven.

4. Bake cheesecake in preheated moderate oven (375 degrees) for 50-60 minutes or until set. Check pan of water occasionally to make sure water hasn't evaporated; add water, if necessary. Cool on wire rack.

Nut Crust: Combine 1 cup all-purpose flour, 1/4 cup firmly packed light brown sugar and 1/4 cup ground walnuts, almonds or pecans in medium-size bowl. Cut in 1/4 cup (1/2 stick) butter with fingers or 2 forks until well blended.