In a food processor, combine flour, powdered sugar, almond flour, salt, and the zest of one orange. Pulse in chilled butter until the mixture resembles coarse crumbs. Next, add the egg yolk and cold water, combining just until a dough forms. Wrap the dough in plastic wrap and chill it in the refrigerator for at least 15 minutes.

Preheat your oven to 200°C (390°F). Roll out the chilled dough on a lightly floured surface until it's about ¼ inch thick. Carefully fit the rolled dough into a 9-inch tart pan, ensuring it covers the edges. Chill in the freezer for 10 minutes, then bake with pie weights for 22-27 minutes or until the edges are lightly golden. Let the crust cool completely.

In a saucepan, heat fresh orange juice over medium heat. In a separate bowl, whisk together eggs, superfine sugar, and cornstarch until smooth. Gradually pour the hot orange juice into the egg mixture to temper it. Return this mixture to the saucepan and cook over low heat, stirring constantly, for about 5-7 minutes until thickened. Stir in gelatin and let the curd cool slightly.

Once the orange curd has cooled, pour it into the prepared tart crust, spreading it evenly. Cover the tart with plastic wrap and refrigerate for at least 3 hours, or overnight for best results, until fully set.

To prepare the topping, whip the heavy cream until soft peaks form, then fold in a touch of sweetener if desired. Remove the set Classic Orange Tart from the fridge, dollop the whipped cream on top, and garnish with fresh orange segments and mint leaves. Slice the tart and serve chilled.