In a bowl, whisk together flour, sugar, and salt for the pie dough.
Cut in cold butter and shortening until the mixture resembles coarse crumbs.
Add ice water one tablespoon at a time, mixing just until the dough holds together.
Shape the dough into a disk, wrap it, and refrigerate for 30 minutes.
Roll out the dough on a floured surface, fit into a 9-inch pie plate, trim edges, and crimp or decorate as desired. Chill while preparing the filling.
Preheat oven to 350°F (175°C).
In a large bowl, whisk melted butter and sugar until combined.
Add egg yolks one at a time, mixing well after each addition.
Stir in flour until smooth, then gradually whisk in milk, lemon juice, and lemon zest.
In a separate bowl, beat egg whites until stiff peaks form, then gently fold into the lemon mixture without overmixing.
Pour the filling into the prepared crust.
Bake for 45 to 55 minutes, until the center is set but slightly jiggles.
Cool completely for at least 2 hours before slicing.
For optional raspberry sauce, combine raspberries and sugar in a saucepan over medium heat. Mix cornstarch with water and stir into the berries. Simmer until thickened, then cool.
For optional whipped cream, beat whipping cream until soft peaks form, add powdered sugar to taste, and continue beating to desired thickness.
For optional raspberry frosting, beat cream cheese and butter until smooth. Blend and strain raspberries and mix into cream cheese mixture. Gradually beat in powdered sugar until fluffy.