You and your family will obsess over this orange and lemon tart. It takes a bit of time to make, but you will be so happy when it's done.
Tart shell:
1 large egg, separated
1 T. milk
1 1/4 c. + 2 T. all-purpose flour
4 t. sugar
1/8 t. salt
1 stick cold unsalted butter, cut into 1/2-inch cubes
Filling:
4 large eggs
1 1/2 c. sugar
2 t. orange zest, finely grated
1 1/2 t. lemon zest, finely grated
1/2 c. freshly squeezed orange juice
1/2 c. freshly squeezed lemon juice
1/4 c. heavy cream
Tart shell:
Lightly beat yolk with milk in a small bowl, reserving white for egg wash. Pulse together flour, sugar and salt in a food processor. Add butter; pulse until mixture resembles coarse meal with some roughly pea-size butter lumps. Add yolk mixture; pulse just until dough begins to gather into a ball. Press dough into a ball, then flatten into a 6-inch disk. Chill, wrapped in plastic wrap, at least 1 hour.
Place oven rack in middle position; preheat oven to 350 degrees.
Let dough soften slightly at room temperature for about 20 minutes.
Roll out dough between sheets of plastic wrap into a 12-inch round. Discard top sheet; invert dough into 9 1/2 inch round fluted tart pan with a removable bottom; discard remaining plastic wrap. Fit dough into pan, pushing edge of dough to 1/8 inch above rim. Trim dough, saving scraps to repair any cracks in partially baked shell.
Freeze shell until firm, about 10 minutes.
Line shell with parchment paper or foil; fill with pie weights.
Bake until edge is golden and bottom is set, about 20 minutes. Carefully remove pie weights and parchment; gently prick any bubbles with a fork to release air; bake until bottom is pale golden, 10 - 15 minutes. Quickly repair any cracks in shell with reserved scraps; immediately brush hot pastry all over with egg white. Keep oven on.
Filling and bake tart:
Whisk together all filling ingredients until combined well. Put tart shell which is in the tart pan, on a baking sheet; place in the oven. Carefully pour filling into shell; put a pie shield or foil strips over rim of pastry to prevent burning.
Bake tart until filling is barely set, but trembles slightly in center when gently shaken, about 20 - 25 minutes. Cool completely in pan on a rack, about 45 minutes. The filling will continue to set as it cools.
6 servings.
* Dough can be chilled and fitted into the tart pan, but not baked 1 day in advance.
** Filling can be made 1 day in advance and chilled, covered. Bring to room temperature before using.
*** Tart can be baked 3 hours in advance and cooled completely, then kept at room temperature.