Makes 2 large crusts, or 8 small crusts.
In a food processor, cream together:
12 tablespoons butter (1½ sticks), cold
½ cup sugar
Add and mix well:
¼ teaspoon salt
1 egg yolk
2 teaspoons vanilla extract
1 teaspoon lemon juice
Add and mix together by pulsing:
2¼ cups flour
On a floured surface, divide the dough into 2 balls and chill for at least 1 hour.
Preheat the oven to 400°f.
Roll out pastry crust on a lightly floured sheet of parchment paper until it is about ¼-inch thick and 12 inches in diameter.
Spread on the rolled-out dough a thin film of:
3 tablespoons berry jam (optional)
Pile in the middle of the dough, leaving about a 2-inch border:
1 quart blueberries (or any combination with blackberries, raspberries, or black raspberries)
Fold the dough up over the berries and brush lightly with:
1 egg, lightly beaten
Dot the berries with:
2 tablespoons butter, cold, thinly sliced
Sprinkle over the dough and berries:
3 tablespoons sugar
Transfer the tart and parchment paper to a cookie sheet and bake until the pastry is nicely golden, about 40–50 minutes.
Serve warm or at room temperature, plain or with:
Fresh whipped cream, ice cream, or fresh berries