Prepare the Peanut Butter Crust: Combine flour, peanuts, brown sugar, and salt in bowl of a food processor; process until peanuts are ground and mixture is combined. Add butter, peanut butter, and shortening, and pulse until mixture resembles small peas, 10 to 12 times. Sprinkle 4 tablespoons ice water over top of mixture. Pulse 4 times. Add up to 2 more tablespoons of water, 1 tablespoon at a time, pulsing after each addition until dough just begins to clump together. Remove dough from processor; shape and flatten into a disk. Wrap disk in plastic wrap, and chill 2 hours or up to 2 days.
Preheat oven to 375°F. Place chilled dough disk on a lightly floured piece of parchment paper. Sprinkle dough with flour. Top with another piece of parchment paper. Roll dough into a 13-inch circle. Remove and discard top sheet of parchment. Starting at 1 edge of dough, wrap dough around rolling pin, separating dough from bottom sheet of parchment as you roll. Discard bottom sheet of parchment. Place rolling pin wrapped with dough over a 9-inch (1 1/2-inch-deep) glass pie plate. Unroll dough, and gently press it into pie plate. Trim dough, leaving 1/2-inch overhang; fold edges under, and crimp.
Prepare Peanut Butter Filling: Stir together brown sugar, flour, and kosher salt in a large bowl. Stir in melted butter. Whisk eggs well in a medium bowl; whisk in milk, sorghum, and vanilla. Add peanut butter; whisk until blended. Spoon filling into prepared piecrust. Sprinkle peanuts over top, and place pie on a rimmed baking sheet.
Bake in preheated oven 10 minutes. Reduce oven temperature to 350°F, and bake until puffed and golden brown and until center is set, 45 to 55 minutes, shielding edges with aluminum foil to prevent overbrowning, if necessary. Transfer pie to a wire rack, and cool completely, about 2 hours.
Prepare the Brown Sugar-Bourbon Whipped Cream: Using chilled beaters and a large chilled bowl, beat whipping cream with an electric mixer on high speed until thickened, about 2 minutes. Add sugar, and beat until stiff peaks form, about 2 minutes. Add bourbon and vanilla, and beat until well combined. Cover and chill until ready to serve.