01 - Pulse pistachios in a food processor until finely ground. Add flour, powdered sugar, and salt; pulse to combine. Add cold butter and pulse until coarse crumbs form. Add egg yolk and pulse a few times. Drizzle in ice water, 1 tablespoon at a time, pulsing just until dough begins to clump.
02 - Press dough evenly into the bottom and sides of a 9-inch tart pan with removable bottom. Refrigerate for 20 minutes to firm up.
03 - Preheat oven to 350°F.
04 - Line the chilled crust with parchment paper and fill with pie weights or dried beans. Bake for 15 minutes. Remove weights and parchment, then bake for 8 more minutes until golden brown. Cool slightly.
05 - In a mixing bowl, whisk eggs and sugar until smooth. Add orange zest, juice, cardamom, heavy cream, melted butter, and salt; whisk until fully blended.
06 - Pour the filling into the slightly cooled crust. Reduce oven temperature to 325°F and bake for 20-22 minutes until the filling is just set but still slightly wobbly in the center.
07 - Cool the tart at room temperature, then refrigerate for at least 1 hour to fully set before serving.
08 - Sprinkle chopped pistachios over the top and add orange zest strips or candied orange slices as garnish. Serve chilled.