In a food processor, pulse together flour, powdered sugar, almond flour, salt, and orange zest until mixed well. Add chilled butter and pulse until the mixture resembles coarse crumbs. Then, mix in the egg yolk and cold water until a dough forms. Wrap the dough and chill in the refrigerator for at least 15 minutes to firm up.

Preheat your oven to 390°F (200°C). Roll out the dough to fit a 9-inch tart pan, then carefully transfer it into the pan and refrigerate it while preparing for blind baking. Line the crust with parchment paper and fill it with pie weights. Bake for 12-15 minutes, then remove the weights and continue baking for an additional 10-12 minutes until the crust is golden brown.

In a saucepan, heat fresh orange juice until steaming. Meanwhile, in a mixing bowl, whisk together the eggs, superfine sugar, and cornstarch until smooth. Gradually whisk the hot orange juice into the egg mixture, then return the mixture to the pan. Cook over low heat, stirring constantly, for 5-7 minutes until the curd thickens.

Once the curd has thickened, remove it from the heat and stir in the gelatin until fully dissolved. Allow the curd to cool slightly before incorporating the butter and additional orange zest, stirring until well blended.

Pour the silky orange curd filling into the baked crust, smoothing the top with a spatula. Cover with plastic wrap and refrigerate for at least 3 hours, but overnight is ideal to let the flavors deepen and the filling set properly.

Just before serving, whip the heavy cream with a touch of sugar until soft peaks form. Garnish the chilled classic orange tart with the whipped cream, and sprinkle with crushed pistachios, fresh mint, or additional orange segments.