Provencal Vegetable Tian

Ingredients

• 6 tablespoons extra-virgin olive oil, divided
• 2 cups thinly sliced leeks, white and pale-green parts only, rinsed well (1 large leek)
• 1 yukon gold potato (8 ounces), sliced 1/4 inch thick
• coarse salt and freshly ground pepper
• 1 small eggplant (12 ounces), trimmed and sliced 1/4 inch thick
• 1 large zucchini (8 ounces), sliced 1/4 inch thick
• 3 large beefsteak tomatoes, sliced 1/4 inch thick
• 1/4 cup pitted kalamata olives, pitted and roughly chopped
• 2 teaspoons fresh thyme leaves, divided, plus more for garnish