In a bowl, mix flour and salt. Cut in cold butter until crumbly. Gradually add ice water to form a dough. Wrap in plastic wrap and chill for 30 minutes.

Heat olive oil in a skillet over medium heat. Add fennel and leeks; season with salt and pepper. Sauté until soft and golden, about 15 minutes.

Preheat oven to 400°F (200°C). On a floured surface, roll out the chilled dough into a rough circle (12 inches wide).

Transfer dough to a parchment-lined baking sheet. Spoon sautéed veggies into the center, leaving a 2-inch border. Sprinkle with Parmesan.

Fold the edges of the dough over the filling while pleating for an open-faced tart look. Brush exposed crust with olive oil.