This Zucchini Tomato Gratin is a colorful, nutrient-packed dish perfect for busy weeknights.
Layers of tender zucchini, potatoes, and juicy tomatoes bake in a flavorful tomato sauce, making it both satisfying and wholesome.
Rich in fiber, plant-based protein, and heart-healthy fats, it’s low in saturated fat and naturally gluten-free, making it an ideal, easy-to-make choice for everyday meals.
Wholesome Zucchini Tomato Gratin
Equipment
- 2-quart baking dish
- Mandoline slicer (optional, for even slicing)
- Aluminum foil
- Mixing bowl
- Knife
- Cutting board
Ingredients
- 1 cup tomato sauce
- 4 cloves garlic minced
- 2 tablespoons olive oil divided
- 2 teaspoons Italian seasoning divided
- 3 –4 medium tomatoes sliced ¼-inch thick
- 2 small zucchini sliced ¼-inch thick
- 3 –4 small Yukon Gold potatoes sliced ⅛-inch thick
- Salt to taste
- Freshly ground black pepper to taste
- ½ cup shredded parmesan cheese
- Chopped fresh parsley for garnish
Instructions
- Preheat the Oven: Begin by preheating your oven to 375°F (190°C). This ensures that the baking dish and the vegetables will cook evenly once assembled. While the oven warms up, gather all your prepared ingredients to keep the cooking process smooth and organized.
- Prepare the Tomato Sauce Base: In a medium mixing bowl, combine 1 cup of tomato sauce with the minced garlic, 1 tablespoon of olive oil, and 1 teaspoon of Italian seasoning. Stir well until the garlic is evenly distributed and the sauce has a fragrant, herby aroma. This mixture will serve as the flavorful foundation for your gratin.
- Coat the Baking Dish: Take a 2-quart baking dish and lightly coat the bottom with a thin layer of the tomato-garlic sauce mixture. Use a spatula or the back of a spoon to spread it evenly, ensuring every corner of the dish has some sauce. This prevents the vegetables from sticking and adds flavor throughout the dish.
- Slice the Vegetables Evenly: Using a sharp knife or a mandoline slicer, slice the zucchini and tomatoes into ¼-inch thick rounds and the Yukon Gold potatoes into ⅛-inch thick rounds. Consistent thickness is crucial for even cooking and presentation. Take care when using a mandoline, as the blade is extremely sharp.
- Arrange the Vegetables in Layers: Begin layering the vegetables upright in the baking dish. Alternate slices of tomato, zucchini, and potato in a tightly packed row, standing the slices against one another. Continue layering in this pattern until the entire dish is filled. The alternating colors and textures create a visually appealing presentation and ensure each bite has a balanced mix of flavors.
- Season the Vegetables: Sprinkle the remaining 1 teaspoon of Italian seasoning evenly over the arranged vegetables. Add salt and freshly ground black pepper to taste. Drizzle the remaining 1 tablespoon of olive oil over the top to enhance flavor and help the vegetables roast evenly.
- Cover and Bake Initially: Cover the baking dish tightly with aluminum foil to trap moisture and allow the vegetables to steam gently. Place the dish in the preheated oven and bake for 35 minutes. This step softens the vegetables and allows the flavors to meld together.
- Add Cheese and Continue Baking: Carefully remove the aluminum foil. Sprinkle ½ cup of shredded parmesan cheese evenly over the top of the vegetables. Return the dish to the oven and bake uncovered for an additional 20–30 minutes. The cheese will melt, bubble, and form a golden, slightly crisp crust, while the vegetables finish cooking and become tender.
- Rest Before Serving: Once the gratin is fully cooked, remove it from the oven and allow it to rest for 10 minutes. This step helps the vegetables set slightly, making it easier to serve without the layers collapsing.
- Garnish and Serve: Before serving, sprinkle the top with freshly chopped parsley for a pop of color and fresh flavor. Serve warm as a satisfying main dish or side, perfect for weeknight dinners, meal prep, or special occasions.
Notes
- For uniform cooking, slice all vegetables evenly. A mandoline works best for consistent thickness, but handle carefully.
- Use firm, ripe tomatoes and small Yukon Gold potatoes for optimal texture.
- If you prefer a richer flavor, add a teaspoon of butter or a drizzle of extra virgin olive oil before baking.
- Parmesan cheese can be swapped with mozzarella or Gruyère for a different taste profile.
- This recipe can be made ahead of time and baked just before serving.
Chef’s Secrets: Elevate Gratin Flavors Naturally
To make your gratin truly outstanding, allow the tomato sauce to sit with the minced garlic for 10–15 minutes before spreading it in the dish.
This enhances the aroma and infuses the sauce with depth. Using a mandoline ensures perfectly even slices, which cook at the same rate and create a professional, layered presentation.
For added richness, try lightly roasting the potato slices beforehand—this adds a subtle caramelized flavor without extra effort.
Lastly, finishing the gratin under the broiler for 2–3 minutes gives the cheese a beautiful golden crust.
Serving Suggestions: Perfect Pairings For Meals
This zucchini tomato gratin pairs wonderfully with a variety of proteins and grains.
Serve alongside grilled chicken, seared fish, or a plant-based protein like chickpea patties for a balanced meal.
It also works beautifully as a side dish for pasta, risotto, or quinoa bowls.
For a lighter option, enjoy it on its own with a fresh green salad.
Garnishing with fresh parsley or a sprinkle of chili flakes adds a fresh, zesty touch before serving.
Storage Tips: Keep Gratins Fresh Longer
Leftovers can be stored in an airtight container in the refrigerator for up to 3–4 days.
Reheat gently in a 350°F (175°C) oven to retain the texture, or use a microwave for convenience.
If you want to make it ahead for meal prep, assemble the gratin without the cheese, cover tightly with foil, and refrigerate for up to 24 hours—add the cheese and bake just before serving.
This keeps the vegetables from becoming too soft.
Frequently Asked Questions
1. Can I make this gratin vegan?
Yes! Replace the parmesan cheese with a vegan cheese alternative or nutritional yeast. You can also drizzle a little extra olive oil for richness.
2. Can I use frozen vegetables?
Fresh vegetables give the best texture, but if using frozen zucchini or potatoes, make sure to thaw and pat dry to prevent excess water from making the gratin soggy.
3. Can I prepare this dish in advance?
Absolutely. Assemble the layers and refrigerate for up to 24 hours. Bake with cheese added just before serving to maintain a fresh, crisp topping.
4. What other cheeses can I use instead of parmesan?
Mozzarella, Gruyère, or Pecorino Romano are excellent alternatives. For a lighter flavor, a sprinkle of feta adds tanginess without overwhelming the dish.
5. How do I prevent the vegetables from being mushy?
Slice vegetables evenly and avoid overcrowding the baking dish. Covering initially helps them steam, but baking uncovered for the final 20–30 minutes ensures they become tender but not mushy.
