FOR THE TART SHELL:
1 ˝ cups all-purpose flour
⅓ cup confectioners’ sugar
Grated zest of 1/2 lemon
Pinch kosher salt
˝ cup (1 stick) unsalted butter, cold and cubed
1 large egg, lightly beaten
FOR THE TART SHELL::
˝ cup blanched sliced almonds
FOR THE PASTRY CREAM:
1 large, unsprayed, fragrant rose (about 1 cup petals), or 1/2 teaspoon rosewater
2 cups whole milk
⅓ cup all-purpose flour
⅓ cup sugar
5 large egg yolks
1 to 2 pints raspberries, blueberries or hulled strawberries
For the crust, place 1/4 cup flour and the almonds in a food processor. Run until the almonds are finely ground, about 1 minute. Pulse in remaining one and a quarter cups flour, sugar, lemon zest and salt.
Add the butter and pulse until a coarse meal forms. Add the egg and pulse until the dough comes together. Press dough into a disk, wrap in plastic, and chill for 4 hours or up to a week.
To make the pastry cream, pull the rose petals from the stem and drop into a heavy saucepan. Pour in milk and bring to a simmer. Remove from heat, cover, and let stand 1 hour. Strain and discard petals; pour liquid into pot and return to a simmer. (If you are using rosewater, skip the steeping; bring milk to a simmer and stir in the rosewater off the heat.)
In a medium bowl, whisk flour and sugar. Slowly whisk in the hot milk. Return mixture to the saucepan and cook over medium heat, stirring constantly, until mixture just starts to boil, 1 to 2 minutes.
In a large bowl, whisk yolks until pale and thick. Whisking constantly, pour the hot milk mixture into the yolks. Return the mixture to the saucepan. Cook over medium-low heat, stirring constantly, until custard is thick and smooth (170 degrees on an instant-read thermometer). Do not let the mixture boil. Strain through a fine-mesh sieve. Chill 1 hour before using or up to 5 days.
When ready to bake the tart, roll the dough out between two sheets of plastic to a 3/8-inch thickness. Remove plastic and line a 9-inch tart pan with the dough; chill for 30 minutes.
Heat the oven to 325 degrees. Line the tart shell with foil and fill with baking weights. Bake for 20 minutes, then remove the foil and weights. Continue baking, uncovered, for 5 to 10 more minutes, until pale golden. Allow tart shell to cool completely before filling.
Spoon chilled pastry cream into cooled tart shell. Arrange berries over the top of the tart. Serve within 2 hours for the best texture.