In a food processor, combine flour, powdered sugar, almond flour, salt, and zest of one orange. Pulse until mixed; add chilled butter and process until resembling coarse crumbs. Incorporate egg yolk and enough cold water to form a shaggy dough. Chill the dough for 15-60 minutes.

Roll out chilled dough to fit a 9-inch tart pan, transferring it carefully into the pan. Freeze the shell for 30 minutes. Blind-bake at 200°C for 12-15 minutes until lightly golden, then bake an additional 5-10 minutes after removing weights.

Gently heat fresh orange juice in a saucepan. Whisk egg yolks, superfine sugar, and cornstarch together until smooth. Temper the egg mixture by whisking in warm orange juice. Pour back into the saucepan, cook on low heat, stirring constantly until thickened. Stir in gelatin and butter until melted.

Once cooled, pour orange curd into the pre-baked tart shell, spreading evenly. Cover and refrigerate for at least 3 hours or overnight.

Before serving, whip heavy cream with powdered sugar until stiff peaks form. Garnish the tart with dollops of whipped cream, crushed pistachios, and fresh mint leaves.