Lemon Sponge Pie

From 6 Bittersweets
Adapted from from Betty Crocker Baking Classics (out of print) via The Food Librarian

XIAOLU'S NOTE: As I've done before, to bring out the citrus flavor even more, I used a technique from Dorie Greenspan. I rubbed all the zest into the sugar until it was fragrant with orange. I added this where the original recipe says to add sugar.

Your favorite single crust pie crust [I used this one]
3 large eggs, separated
2 T grated lemon peel [I used a microplane to zest the lemons]
2/3 cup regular or Meyer lemon juice [I used regular]
1 cup milk
1 1/4 to 1 1/2 cups sugar, depending on how tart you like things
1/3 cup flour
1/4 tsp salt

Preheat oven to 350 degrees F.

Roll out crust and line pie pan with crust. Leave unbaked and chill in fridge while you prepare the filling.

Beat egg yolks; beat in lemon peel, lemon juice and milk. Add sugar, flour and salt; beat until smooth.

In a separate large bowl, beat egg whites with an electric mixer until stiff peaks form. Add 1/3 of the egg whites to the lemon mixture and beat them together thoroughly.

Fold the lightened lemon mixture into the remaining egg whites, stopping when there are no white streaks remaining. Pour into pastry-lined pie plate. Bake until golden brown, 45 to 50 minutes. (A layer of lemon will settle to the bottom and a soft meringue-like topping to float to the top.) Serve with sweetened whipped cream if desired.