This zucchini tomato gratin is a simple, colorful vegetable bake made with tender zucchini, ripe tomatoes, garlic, herbs, Parmesan, and a crisp breadcrumb topping. It is a light side dish that pairs beautifully with grilled chicken, fish, steak, or crusty bread.deliciousmeetshealthy
Why You’ll Love It
- Uses fresh summer vegetables.
- Easy to assemble in one baking dish.
- Naturally vegetarian.
- Full of garlic, herb, and Parmesan flavor.
- Works as a side dish or light vegetarian main.
- Can be served warm or at room temperature.
Ingredients
- 2 medium zucchini, sliced into thin rounds.
- 3 medium tomatoes, sliced into rounds.
- 1 small onion, thinly sliced.
- 2 garlic cloves, minced.
- 2 tablespoons olive oil, divided.
- ½ teaspoon dried oregano.
- ½ teaspoon Italian seasoning.
- Salt and black pepper, to taste.
- ½ cup grated Parmesan cheese.
- ½ cup panko breadcrumbs.
- 2 tablespoons chopped fresh basil or parsley.
- Pinch of red pepper flakes, optional.
Instructions
Prepare the vegetables
Preheat the oven to 375°F.
Lightly grease an 8×8-inch or similar-sized baking dish.
Slice the zucchini and tomatoes into even rounds. If the tomatoes are especially juicy, place the slices on paper towels for several minutes to absorb some of the liquid.
Make the garlic oil
Heat 1 tablespoon of olive oil in a small skillet over medium heat.
Add the sliced onion and cook for 3–4 minutes, until softened. Stir in the garlic and cook for 30 seconds, until fragrant.
Remove the skillet from the heat.
Arrange the gratin
Spread about one-third of the onion and garlic mixture across the bottom of the baking dish.
Arrange the zucchini and tomato slices in overlapping rows or in a circular pattern. Alternate the vegetables for a colorful presentation.
Spoon the remaining garlic and onion mixture over the top.
Drizzle with the remaining olive oil. Sprinkle with oregano, Italian seasoning, salt, black pepper, and red pepper flakes if using.
Add the topping
In a small bowl, combine the Parmesan cheese, panko breadcrumbs, and chopped basil or parsley.
Sprinkle the topping evenly over the arranged vegetables.
Bake
Cover the dish loosely with aluminum foil and bake for 25–30 minutes, until the vegetables begin to soften.
Remove the foil and continue baking for 10–15 minutes, until the topping is golden and the vegetables are tender.
Let the gratin rest for 5–10 minutes before serving.
Recipe Tips
- Salt the zucchini lightly and pat it dry to reduce excess moisture.
- Use firm, ripe tomatoes rather than overly soft ones.
- Slice the vegetables evenly so they cook at the same rate.
- Do not overcrowd the dish with several thick layers.
- For extra browning, broil the gratin for 1–2 minutes at the end.
- Let the dish rest before serving so the juices settle.
- Add fresh basil after baking for a bright finish.
Ingredient Variations
Add cheese
Use mozzarella, Gruyère, Asiago, cheddar, or feta along with or instead of Parmesan.
Add vegetables
Include thinly sliced yellow squash, eggplant, potatoes, bell peppers, or mushrooms.
Make it gluten-free
Replace regular panko breadcrumbs with gluten-free breadcrumbs or crushed gluten-free crackers.
Make it vegan
Use a plant-based Parmesan alternative and vegan breadcrumbs.
Add protein
Serve the gratin with grilled chicken, baked fish, or white beans. Chopped cooked chicken can also be layered between the vegetables.
Serving Suggestions
Serve zucchini tomato gratin with:
- Grilled chicken breasts.
- Roasted salmon.
- Baked white fish.
- Grilled steak.
- Turkey meatballs.
- Crusty bread.
- Quinoa or brown rice.
- A simple green salad.
It can also be served as a light vegetarian lunch with a spoonful of Greek yogurt or a fresh bean salad.
Make-Ahead Instructions
Slice the vegetables and prepare the breadcrumb topping up to several hours in advance.
Store the components separately in the refrigerator. Assemble the gratin shortly before baking for the best texture.
You can also bake the gratin ahead of time and serve it warm or at room temperature.
Storage and Reheating
Store leftovers in an airtight container in the refrigerator for up to 3 days.
Reheat in a 350°F oven until warmed through. Individual portions can also be reheated in the microwave, although the topping will be softer.
Freezing is not recommended because zucchini and tomatoes release water when thawed.
Frequently Asked Questions
Why is my gratin watery?
Zucchini and tomatoes both contain a lot of water. Pat the vegetables dry, use firm tomatoes, avoid overcrowding the dish, and allow the gratin to rest after baking.
Can I use cherry tomatoes?
Yes. Halve the cherry tomatoes and arrange them over the zucchini. They may release less liquid than large tomatoes.
Can I prepare this with potatoes?
Yes. Thinly sliced potatoes can be added, but they may need additional baking time. Cover the dish until the potatoes are tender before browning the topping.
Can I make this without breadcrumbs?
Yes. Use Parmesan alone, or replace the breadcrumbs with almond flour, crushed nuts, or extra shredded cheese.
Nutrition Information
Nutrition will vary depending on the amount of olive oil, cheese, breadcrumbs, and vegetables used.
For a lighter version, reduce the oil and Parmesan. For a lower-carbohydrate version, replace the breadcrumbs with almond flour or additional Parmesan.
