Preheat the oven to 325F. Line an 8x8 pan with foil, with the ends extending over the sides.
Mix the wafer crumbs with the melted butter until blended. Press the mixture into the bottom of the pan. Bake 10 minutes. Cool.
Separate 1 egg white and refrigerate the yolk (covered with plastic) until ready to use. In a large bowl beat the cream cheese, ½ cup sugar, flour, zest, 1 Tablespoon of juice, and vanilla until completely smooth. Mix the egg white and remaining 2 eggs one at a time on low speed.
Pour the batter over the crust and bake 40 minutes or until the center is set. Cool 1 hour. Refrigerate for at least 4 hours.
Mix the corn starch and remaining sugar in a saucepan. Gradually stir in water and remaining lemon juice until blended. Bring the mixture to a boil over medium heat while stirring constantly. Cook until thickened.
Beat the yolk in a bowl until blended. Stir in 1-2 Tablespoons of the hot cornstarch mixture. Return the yolk mixture to the rest of the corn starch mixture and stir until blended. Cook for 1 minute while stirring constantly. Cool slightly.
Spoon the lemon glaze over the cheesecake. Refrigerate for 1 hour or until firm. Use the foil handles to remove the cheesecake from the pan.
Cut into squares and wipe the knife between cuts to get clean squares.