• Combine the flour, sugar, and salt in a small bowl and place in the freezer for 30 minutes.
• Put the flour mixture in the bowl of a food processor fitted with a steel blade.
• Add the butter and shortening and pulse about 10 times, or until the butter is in the size of peas.
• Add the ice water and process until the dough comes together. Dump on a well-floured board and form into a disk. Wrap in plastic and chill for at least 30 minutes.
• Meanwhile, preheat the oven to 375°F.
• Roll out the dough and fit into a tart pan or 4 (4 1/2-inch) tart pans with removable sides.
• Don't stretch the dough when placing it in the pans or it will shrink during baking.

  Ideally, freeze the dough for at least 15 minute before blind baking.
• Cut off the excess by rolling the pin across the top of each pan. Line the tart shells with a piece of buttered aluminum foil, butter side down, and fill them with dried beans or rice.
• Bake for 10 minutes. Remove the beans and foil, prick the bottom of the shells all over with a fork, and bake for another 15 to 20 minutes until lightly browned. Set aside to cool.

Pastry Cream

• In the bowl of an electric mixer fitted with the paddle attachment, beat the egg yolks and sugar on medium-high speed for 4 minutes, or until very thick. Reduce to low speed, and add the cornstarch.
• With the mixer still on low, slowly pour the hot milk into the egg mixture.
• Pour the mixture into a medium saucepan and cook over low heat, stirring constantly with a wooden spoon, until the mixture thickens, 5 to 7 minutes. Don't be alarmed when the custard comes to a boil and appears to curdle; switch to a whisk and beat vigorously.
• Cook, whisking constantly, for another 2 minutes; the custard will come together and become very thick, like pudding.
• Stir in the vanilla, Cognac (if using), butter, and heavy cream. Pour the custard through a sieve into a bowl. Place plastic wrap directly on the custard and refrigerate until cold.

To serve:

• Fill the tart pan (or shells) with the pastry cream. Arrange the berries decoratively on top of the cream.

  Melt the apricot jelly with 1 teaspoon of water and brush the top of the tarts. Sprinkle with pistachios, if using, and serve.