Lemon Cheesecake

1 cup graham cracker crumbs
3 tablespoons sugar
3 tablespoons butter, melted
3 (8 oz) packages Philadelphia Cream Cheese
1 cup sugar
3 tablespoons flour
2 tablespoons lemon juice
1 tablespoon lemon peel, grated
1/2 teaspoon vanilla
4 eggs, 1 separated
3/4 cup sugar (additional)
2 tablespoons corn starch
1/2 cup water
1/4 cup lemon juice
lemon slices

Combine crumbs, 3 tablespoons sugar and margarine. Press into bottom of a 9 inch spring-form pan. Bake at 325 degrees for 10 minutes.
Combine softened cream cheese, 1 cup sugar, flour and lemon juice, lemon peel and vanilla mixing with an electric mixer until well blended. Blend in 3 eggs (one at a time to avoid lumps)and 1 egg white. Reserve 1 yolk. The batter should be smooth with no lumps.  Pour over crust. Bake at 450 degrees for ten minutes. Reduce oven to 250 degrees and continue baking for 30 minutes. Loosen cake from rim of pan and cool. Remove.
In saucepan, combine 3/4 cup sugar and corn starch. Gradually add water and lemon juice. Cook stirring constantly until clear and thickened. Stir small amount of hot mixture into reserved egg yolk. Return to hot mixture. Cook 1 minute, stirring constantly. Spoon over cheese cake. Chill. Garnish with lemon slices if desired.
Note: Put small pan of water in oven while baking cake.