1 cup sugar, plus more for caramelizing the tart
1 tablespoon grated orange zest
2 teaspoons orange flower water (optional but really amps up the flavor)
About 1 cup orange marmalade
First, make the pastry. Place the flour, confectioners’ sugar, and salt in a food processor and pulse 5 or 6 times, just to combine. Add the butter and pulse until the mixture resembles coarse meal.
Transfer the flour mixture to a bowl and, using two forks, stir in the egg yolk mixture until it is evenly distributed. Pinch a piece of dough between your fingers. If it doesn’t hold together, stir in the ice water. Gather the dough into a ball. Lightly flour a work surface, then flatten the ball into a disk, wrap it in plastic, and refrigerate for at least 2 hours. (The pastry can be prepared up to 2 days ahead.)
Place the disk of dough between two pieces of lightly floured parchment paper and roll it out to an 11-inch circle. Transfer the dough to a 9-inch tart pan with a removable bottom, press it into the side of the pan, and trim the overhang. Freeze, covered with aluminum foil, for 20 minutes.
While the pastry is chilling, position a rack in the center of the oven and preheat the oven to 400°F.