Using an electric mixer, beat yolks and sugar until pale.
Add cream cheese, lemon juice and zest, and vanilla.
Beat until smooth.
In another bowl, beat egg whites and cream of tartar until peaks form.
Fold 1/4 of the whites into the cheese mixture to lighten it.
Fold in remaining whites. Spoon into crust.
Bake until filling is firm to touch, about 20 minutes.
Cool on rack. Refrigerate 1 hour.