Preheat your oven to 450 degrees F. Beat shortening and cream cheese in a large bowl with an electric mixer on medium speed until fluffy. Beat in flour and salt until dough forms. Place it in a 9-inch pie plate and press the pie dough into the pie plate and up the sides. Bake 9 to 11 minutes, or until the crust is golden or lightly browned. Remove from the oven and let cool.
Prepare the filling:
In a medium saucepan, whisk together the sugar and cornstarch. Whisk in the half and half and lemon juice. Heat over medium until hot to touch. In a small bowl, use a fork to beat the egg yolks. Beat in a little bit of the hot liquid, then beat in a little bit more and a little bit more... until the eggs have warmed up. Slowly whisk the eggs into the hot mixture. Cook over medium heat until it comes to a full boil, whisking constantly. Remove from heat. Add butter and lemon zest and stir until the butter is melted. Set aside to cool slightly.
Prepare the topping:
In a medium bowl, use an electric hand mixer to whip the whipping cream to soft peaks, then beat in the sugar.
Assemble the pie:
Whisk the sour cream into the warm filling mixture, then scrape the filling into the baked pie crust. Spread the whipped cream on top of the lemon layer. Sprinkle pieces of lemon peel on top, if desired. Refrigerate for at least 2 hours before serving.