Instructions:
- Phase 1: The Crust. Whisk flour, sugar, and salt. Use a pastry blender or fingertips to cut in the cold, diced butter until the mixture resembles coarse sand.
- Bind the crust dough by mixing in the egg yolk and ice water until a dough just forms. Flatten into a disk, wrap, and chill for at least 1 hour.
- Roll out the chilled dough and press it into a 9-inch tart pan. Prick the bottom well. Line with parchment paper and pie weights, then blind bake at 375°F (190°C) for 15 minutes. Remove weights and bake for another 5-7 minutes until lightly golden. Let cool slightly.
- Phase 2: The Curd. In a medium, heavy-bottomed saucepan, whisk together the whole eggs, extra yolks, sugar, orange juice, lemon juice, and orange zest until homogenous.
- Cook the mixture over medium-low heat, whisking constantly, until it thickens enough to coat the back of a spoon (reaching about 170°F/77°C). Do not allow it to boil.
- Remove from heat. Immediately pass the warm curd through a fine-mesh sieve into a clean bowl to ensure it is perfectly smooth.
- Whisk in the cold butter cubes one by one until fully melted and incorporated. Finally, whisk in the 2 tablespoons of dry sparkling wine.
- Fill the pre-baked crust with the curd. Bake at 325°F (160°C) for 10-12 minutes until the edges are set but the center still has a slight jiggle.
- Cool the tart completely on a wire rack, then refrigerate for a minimum of 3 hours until the curd is fully firm.
- Phase 3: The Glaze. Combine the remaining ½ cup sparkling wine and 2 tablespoons of sugar in a small pan. Simmer gently until the liquid reduces by half and becomes a light syrup.
- Let the reduction cool slightly, then drizzle artfully over the chilled tart just before serving.