Ingredients:

  • 4 large Zucchini (about 900g / 2 lbs), ends trimmed
  • 2 teaspoons Kosher Salt (for draining)
  • 4 tablespoons Extra Virgin Olive Oil (EVOO)
  • 4 cloves Garlic, minced finely
  • 2 teaspoons Dried Herbs de Provence
  • 1 teaspoon Fresh Thyme Leaves
  • 1/2 teaspoon Black Pepper, freshly ground
  • 6–8 medium Ripe Tomatoes (about 800g / 1.75 lbs)
  • Fine Sea Salt, to taste
  • 100g Gruyère or Comté Cheese, freshly grated
  • 50g Parmesan Cheese, finely grated
  • 3 tablespoons Panko Breadcrumbs
  • 1 tablespoon Unsalted Butter, melted

Instructions:

  1. Slice the Vegetables: Using a mandoline or very sharp knife, slice the zucchini and tomatoes into uniform 3mm (1/8 inch) thick rounds. Uniformity is key for even cooking.
  2. Salt and Drain Zucchini: Place the zucchini slices in a large colander set over a bowl. Toss liberally with the 2 teaspoons of Kosher salt. Allow to rest for 30 minutes; this draws out excess moisture.
  3. Pat Dry: After 30 minutes, rinse the zucchini very briefly under cold water to remove residual salt, then spread the slices onto several layers of kitchen paper or a clean tea towel. Pat them vigorously until they are completely dry. (This is essential.)
  4. Preheat and Prepare Dish: Preheat oven to 190°C (375°F). Lightly butter the gratin dish (9x13 inch recommended).
  5. Create Herb Paste: In a small bowl, combine the olive oil, minced garlic, herbs de Provence, fresh thyme, and black pepper.
  6. Coat the Veg: Gently toss the dried zucchini slices with half of the herb-oil paste. Toss the tomato slices with the remaining paste. (Do this gently to keep the slices intact.)
  7. Arrange the Gratin: Start at one end of the dish and tightly layer the vegetable slices, alternating between zucchini and tomato, shingle-style, working in diagonal rows across the dish. Press them down tightly so they are snug.
  8. Final Seasoning: Lightly sprinkle the arranged vegetables with fine sea salt.
  9. Prepare Topping: In a separate small bowl, combine the Gruyère, Parmesan, Panko breadcrumbs, and melted butter.
  10. Top and Bake: Sprinkle the topping evenly over the vegetables, ensuring good coverage.
  11. Bake: Bake for 35–40 minutes, or until the vegetables are tender, the edges are bubbling vigorously, and the topping is deeply golden brown. (If the top browns too quickly, cover lightly with foil.)
  12. Rest: Remove from the oven and allow the gratin to rest for 10 minutes before serving. This allows the internal moisture to settle, preventing the gratin from collapsing when served.