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Tomato Zucchini Gratin with Mozzarella in a white ceramic dish with red handles, topped with melted mozzarella, browned Parmesan, and fresh thyme.

Tomato Zucchini Gratin with Mozzarella

A colorful Mediterranean vegetable bake featuring shingled rounds of zucchini and Roma tomatoes over a garlic tomato sauce, topped with melted mozzarella and golden-browned Parmesan cheese.
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Prep Time 15 minutes
Cook Time 32 minutes
Servings: 6
Calories: 210
Ingredients Method Notes

Ingredients
  

  • 2 medium green zucchinis sliced into ¼-inch thick rounds
  • 4 large Roma tomatoes sliced into ¼-inch thick rounds
  • 1.5 cups marinara sauce or tomato passata
  • 8 oz fresh mozzarella cheese shredded or sliced thin
  • 0.5 cup Parmesan cheese freshly grated
  • 2 tbsp extra virgin olive oil divided
  • 2 cloves garlic finely minced
  • 1 tsp dried Italian seasoning
  • 0.5 tsp sea salt or to taste
  • 0.25 tsp cracked black pepper or to taste
  • 4 sprigs fresh thyme for garnish

Method
 

  1. Prep the Oven and Pan: Preheat your oven to 400°F (200°C).
  2. Build the Base: In the bottom of a large ceramic baking dish, stir together the marinara sauce (or tomato passata), minced garlic, and 1 tablespoon of olive oil until smooth and flat.
  3. Shingle the Vegetables: Alternately shingle the zucchini rounds and tomato slices in tight, overlapping rows across the entire pan on top of the sauce layer.
  4. Season: Drizzle the remaining 1 tablespoon of olive oil over the vegetables. Season evenly with dried Italian seasoning, sea salt, and cracked black pepper.
  5. Add Cheese and Bake: Scatter the shredded mozzarella and grated Parmesan cheese evenly over the top. Bake uncovered for 25 to 30 minutes until the vegetables are tender and the cheese is melted and bubbling.
  6. Broil: Turn the oven to broil and cook for 2 minutes, watching closely until the cheese is spotty golden-brown.
  7. Garnish and Serve: Remove from the oven, garnish with fresh thyme sprigs, and let rest for 5 to 10 minutes before serving.

Notes

  • Use firm Roma tomatoes to reduce excess liquid during baking.
  • Ensure the gratin is baked uncovered so steam can escape freely.
  • Refrigerate leftovers in an airtight container for up to 4 days. Reheat in a 350°F (175°C) oven for best texture.