For the filling:
1 1/3 cup roasted, unsalted pistachio kernels
2 tablespoons flour
¾ cup plus 1 tablespoon sugar
6 oz (1 ½ sticks) unsalted butter, room temperature
½ teaspoon salt
¼ cup roasted, unsalted pistachio kernels coarsely chopped by hand, set aside
For the crust:
1/4 cup very cold water
1 1/3 cup flour
3/4 teaspoon salt
3/4 teaspoon sugar
2 3/4 ounces shortening, cubed and very cold
1 1/2 ounces unsalted butter, cubed and very cold
For the pie crust
In the bowl of an electric mixer, combine ingredients in the order they are listed, starting with water in the bowl first. Using a paddle attachment, mix until all ingredients are combined and a nice dough has been formed. Remove dough from the mixer, wrap in clear plastic wrap and chill in the refrigerator for at least one hour. Once chilled, roll on a well-floured surface into a circle for a 9-inch pie pan.
For the filling
Pulse the pistachios in a food processor until very coarsely chopped (some of the pistachio will be mealy and the remainder will be coarse). Turn pistachios into a mixing bowl, add all other ingredients and combine with a spatula until fully incorporated.
Fill an unbaked pie shell with the pistachio mixture, smooth the top with a spatula, and bake at 350 degrees for 60-70 minutes on a lower rack in the oven, sprinkling the remaining pistachios on top about 2/3 through the baking process. Test for doneness by inserting a clean knife or toothpick in the center—it should come out clean and the filling should not jiggle. The top will be deep golden. If the crust begins to brown before the pie filling is set, cover loosely with aluminum foil and bake until done.
Serve slightly warm with whipped cream or ice cream.