In a food processor, pulse the pistachios until finely ground. In the bowl of a standing electric mixer fitted with the paddle, beat the butter with the granulated sugar at medium speed until pale, about 1 minute. Add the ground pistachios, almond extract and salt and beat until combined. Add the flour and beat at low speed until incorporated and the dough is crumbly.
Scrape the dough into a 9-inch fluted tart pan with a removable bottom. Using the bottom of a glass, press the dough over the bottom and up the side of the tart pan. Refrigerate until chilled, 30 minutes.
Preheat the oven to 300°F Prick the dough all over with a fork. Bake the crust for about 45 minutes, until lightly golden. Transfer to a rack and let cool completely.