Sues Lemon Puddingcakepie

Pie Dough:
1 1/2 cups of all purpose flour
1/4 teaspoon salt
1 cup of vegetable shortening, chilled, and cut into small pieces
cup of ice water

Filling:
6 tablespoons of unsalted butter, room temperature
1 1/2 cups of granulated sugar
4 large eggs, separated, room temperature
1/3 cup of fresh lemon juice
grated zest of 2 large lemons
4 1/2 tablespoons of all purpose flour
1/4 teaspoon salt
1 1/2 cups of milk

Instructions:

To make the dough: In a large bowl, whisk together the flour and salt. Using a pastry blender or two knives, cut in the shortening until the mixture resembles coarse meal. Tossing the flour mixture with a fork, sprinkle in the ice water, mixing just until the dough is moist enough to hold together when pinched between your thumb and forefinger. Gather the dough up to form a thick flat disk and wrap it in waxed paper. Refrigerate for at least 1 hour or overnight. Position a rack in the lower third of the oven and preheat to 425ºF. To make filling: In a medium bowl, using a hand held electric mixer set at high speed, beat the butter until creamy about one minute. add the sugar and continue beating until the mixture is crumbly and pale yellow, about 2 minutes. Beat in the egg yolks, lemon juice, zest,  flour and salt. On low speed, beat in the milk. In a grease - free medium bowl, using a hand held electric mixer ( with clean beaters) set at low speed, beat the egg whites until foamy. Increase the speed to high and beat just until the whites form stiff peaks. Stir about one fourth of the beaten whites into the lemon  mixture, then fold in the remaining whites. On a lightly floured surface, roll out the dough to form a 14 inch circle about 1/8 inch thick. Transfer it to a 10 inch round pie plate. Fold over 1 inch of the excess dough and flute the edges decoratively. Pour in the filing and place the pie plate on a baking sheet. Bake for 10 minutes at 425ºF. Reduce oven temperature to 350ºF. and continue baking until the top of the pie is a deep golden brown and springs back when pressed in the center, about 35 to 40 minutes. Cool the puddingcakepie completely on a wire cake rack before serving.