01 - Process 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 briefly, then drizzle in ice water 1 tablespoon at a time, pulsing just until dough begins to clump together.
02 - Press dough evenly into the bottom and sides of a 9-inch tart pan with removable bottom. Place in refrigerator to chill for 20 minutes.
03 - Preheat oven to 350°F.
04 - Line crust with parchment paper and fill with pie weights or dried beans. Bake for 15 minutes. Remove weights and parchment, then continue baking for 8 more minutes until golden brown. Allow to cool slightly.
05 - Whisk eggs and sugar in a mixing bowl until smooth. Incorporate orange zest, juice, cardamom, heavy cream, melted butter, and salt, whisking until completely blended and smooth.
06 - Pour filling into the slightly cooled crust. Reduce oven temperature to 325°F and bake for 20-22 minutes until filling is just set but still slightly wobbly in the center.
07 - Allow tart to cool at room temperature, then refrigerate for at least 1 hour before serving to fully set the filling.
08 - Top with chopped pistachios and orange zest strips or candied orange slices just before serving.