In the bowl of a food processor fitted with a metal blade, pulse the 1 1/2 cups all-purpose flour, 1 tablespoon finely chopped rosemary leaves, 1 tablespoon thyme leaves, and 3/4 teaspoon kosher salt until blended.
Add the 12 tablespoons (6 oz) unsalted butter and pulse again until the mixture resembles coarse cornmeal with chunks of butter no bigger than small peas, 10 to 15 one-second pulses.
Dump the tart crust mixture into a large bowl and drizzle with 4 tablespoons ice water.
Using a fork, gently mix just until the mixture forms a “shaggy” dough. Squeeze some of the dough in your hand. If it doesn’t hold together, add enough of the remaining water, 1 tablespoon at a time, until the dough does hold together when gently squeezed.
Form the dough into a disc, wrap it in plastic wrap, and refrigerate for at least 1 hour.
Crank the oven to 400°F (204°C). Place the oven rack in the middle position.
On a lightly floured surface, roll out the dough to a 13-inch (33-cm) circle. Ease it into an 11-inch (28-cm) tart pan, fitting it snugly against the sides and bottom of the pan, and trim the excess.
Prick the bottom with a fork and cover with aluminum foil. Fill the tart with pie weights or beans.
Bake the tart crust for 20 minutes. Remove the weights and foil and bake until pale golden, 5 to 10 minutes more. Let cool.