Prepare the Crust: Stir together 3 cups flour, 1 tablespoon sugar, and 1 teaspoon salt in a large bowl. Using a pastry blender, cut butter and shortening cubes into flour mixture until mixture resembles small peas. Using a fork, gradually stir in 8 tablespoons ice water, stirring until dry ingredients are moistened and dough begins to form a ball and pulls away from sides of bowl, adding up to 2 tablespoons more water, 1 tablespoon at a time, if necessary. Turn dough out onto a work surface; divide in half. Shape and flatten each dough half into a disk. Wrap each in plastic wrap, and chill 1 to 24 hours.
Preheat oven to 425°F. Unwrap 1 chilled dough disk, and place on a lightly floured surface. Let stand at room temperature until slightly softened, about 5 minutes. Sprinkle dough with flour, and roll into a 13-inch circle. Fit dough into a 9-inch glass pie plate. Trim dough, leaving 1/2-inch overhang; fold edges under. Prick bottom and sides 8 to 10 times with a fork.
Unwrap remaining chilled dough disk, and place on a lightly floured surface. Lightly sprinkle with flour, and roll into a 12-inch circle. Cut dough with a 1/2-inch veined rose leaf-shaped cutter. Brush some of the beaten egg white around edges of piecrust. Arrange dough leaves, slightly overlapping, around edge of crust, and press to adhere. Brush dough leaves with remaining egg white. Freeze pie 20 minutes. Line piecrust with parchment paper, and fill with pie weights or dried beans.
Bake in preheated oven 14 minutes. Remove weights and parchment paper, and bake until crust has lost its raw dough sheen, 5 to 7 minutes. Transfer to a wire rack, and cool completely, about 30 minutes. Reduce oven temperature to 350°F.
Prepare the Pumpkin Filling: Whisk together pumpkin, pie spice, 1 1/2 cups sugar, 3 tablespoons flour, and 1/2 teaspoon salt until blended. Whisk in melted butter until blended. Whisk in eggs, vanilla, and 1/2 cup cream until blended. Spoon pumpkin mixture into prepared piecrust. (Piecrust will appear almost full, but there is just the right amount of room for the Lemon-Cream Cheese Filling.)
Prepare the Lemon-Cream Cheese Filling: Stir together cream cheese, zest, egg yolk, 1/4 cup sugar, and 2 tablespoons cream until blended. Spoon cream cheese filling, by rounded teaspoonfuls, over Pumpkin Filling; gently swirl with the tip of a knife.
Bake at 350°F until center is just set, 50 to 60 minutes, shielding edges with aluminum foil to prevent excessive browning, if necessary. Turn oven off. Let pie stand in oven, with door partially open, 20 minutes (to prevent cracks from forming in filling). Transfer pie to a wire rack, and cool completely, about 3 hours. Serve with sweetened whipped cream.