Serena's Chocolate Lemon-Meringue Tart
1 cup flour
1/4 cup unsweetened Belgian cocoa powder
5 ounces unsalted butter, chilled, cut into 1/2-inch cubes
1/4 cup sugar
1/2 teaspoon salt
1 orange, zest only
Zest and juice of 2 lemons
(about 3 ounces)
3 egg yolks
2 whole eggs
1/3 cup sugar
6 tablespoons sweet butter, sliced
Pinch of salt
1 pint raspberries
3 egg whites
1/2 cup sugar
Pinch of salt
Pastry: Put the flour, cocoa, butter, sugar, and salt in the bowl of a food processor. Pulse 10 times, then slowly add 5 tablespoons ice water while pulsing another 10 times. Place the dough in a plastic bag, and allow to rest for 5 minutes. Form the dough into a disk about 5 inches in diameter. Allow to rest in the refrigerator at least 1 hour or overnight. (May be frozen at this point.)
Filling: Put the orange and lemon zests, lemon juice, yolks, whole eggs, and sugar in a saucepan, and whisk until smooth. Place over medium heat and stir constantly. When warmed through, gradually add the butter, and continue stirring until the mixture coats the back of a spoon. Set aside. (The sauce can be frozen at this point.)
Preheat the oven to 400 degrees. Roll the pastry (between two sheets of plastic wrap or parchment if it is a little soft) to fit a 10-inch tart pan. Prick the base of the tart all over with a fork, and freeze for 15 minutes.
Line the tart shell with aluminum foil, cover the base of the foil with dried beans or pie weights, and bake for 20 minutes. Gently remove the foil and bake for a further 20 minutes. (Cover the edge of the tart shell with foil if it starts to burn.) Remove from the oven, and add raspberries to cover the base of the tart. Pour citrus sauce over the fruit to fill the shell.
Reduce oven temperature to 350 degrees. Return the tart to the oven for 15 minutes to allow the sauce to set. Remove from oven.
Beat the egg whites at room temperature with salt until soft peaks form. Add the sugar gradually, and beat on high speed for 30 seconds more, until glossy, soft peaks form.
Pipe the meringue over the citrus sauce using a large star tip (or swirl the meringue decoratively with the back of a spoon) and return to the oven for 20 minutes, until the meringue is lightly colored. Do not refrigerate or wait more than an hour before serving, as meringue will become soft.