In a mixing bowl, combine flour, butter, and powdered sugar until crumbly. Add egg yolk and mix until a dough forms.

Press the dough into the tart pan and refrigerate for 30 minutes.

Preheat the oven to 350°F (175°C). Bake the crust for 20 minutes or until golden.

In a bowl, whisk together orange juice, champagne, sugar, eggs, and orange zest until well combined.

Pour the filling into the baked crust and bake for an additional 15 minutes.

Let cool before serving.