This zucchini tomato gratin is one of my favorite summertime side dishes. It's delicious, gorgeous, and quite easy to make. Leftovers are very good the next day, gently reheated or even cold.
Gratins are so tasty. I really admire the French for teaching us that the best way to make vegetables taste good is to either generously butter them, or add a layer of cheese and bake them.
Zucchini and tomatoes go very well together. And when layered, alternating, in a casserole dish, they also look gorgeous. All they need is a little olive oil (or butter) and a sprinkling of grated parmesan, and they bake into the perfect gratin!
You'll only need a few simple ingredients to make this tasty gratin. Scroll down to the recipe card for the exact measurements. Here's an overview of what you'll need:
Olive oil spray: You can also drizzle the vegetables with olive oil and brush them with it. I just like the convenience of a spray. Another tasty option is to use melted butter.
Zucchinis: Try to pick young, firm zucchinis with a dark-green skin. These are the most flavorful.
Tomatoes: Plump red tomatoes are best - definitely try to avoid those pale mealy ones that taste like nothing!
Kosher salt and black pepper: If using fine salt, you should reduce the amount you use, or the gratin could end up too salty.
Spices: I like to use garlic powder and dried thyme. The advantage of using garlic powder and not fresh minced garlic is that it coats the vegetables more evenly.
Shredded Parmesan: You can also use finely grated parmesan. They're not the same, but both work in this recipe.
Making this zucchini tomato gratin is so easy! Scroll down to the recipe card for detailed instructions. Here are the basic steps:
You simply alternate layers of sliced tomatoes and zucchini in a greased baking dish, as shown in the photos.
Next, you sprinkle the vegetables with salt, pepper, and spices.
Generously spray them with olive oil and sprinkle them with Parmesan.
Bake until golden brown, about 30 minutes.
Expert tip: use fresh vegetables
Try to use fresh, firm zucchinis and tomatoes in this recipe. It's a simple recipe that heavily relies on the flavor of the vegetables. So tasteless watery supermarket vegetables will simply not do.
Frequently asked questions
Gratin is a baked dish that has a browned crust on the top. It's typically made in a shallow baking dish. The crust can contain breadcrumbs, cheese, and butter.
Baking it in high heat helps. Another trick is to salt the zucchini slices and let them stand for 30 minutes in a colander. This will release quite a bit of water, and you can then rinse and dry them and use them in the recipe.
Zucchini, most definitely! It's such a classic combination. This is for cooked recipes. As for salads, tomatoes and cucumbers go well together and so do tomatoes and asparagus.
I like to serve this gratin with chicken or fish. It's very good with crispy baked chicken thighs, and I can bake both dishes in the same oven, which is so convenient.
It's also excellent with baked salmon. Just like the chicken, I find it convenient that I can cook both dishes in the same 425°F oven.
You can keep the leftovers in the fridge, in an airtight container, for 2-3 days. You can gently reheat them in the microwave. Or you can enjoy them cold, served like you would serve antipasto. I love to have cold leftovers for my lunch the next day with some cold meats and cheeses.
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Zucchini Tomato Gratin
- Olive oil spray
- 2 medium firm zucchinis
- 2 medium firm tomatoes
- ½ teaspoon Diamond Crystal kosher salt
- ¼ teaspoon black pepper
- ½ teaspoon garlic powder
- ½ teaspoon dried thyme
- ¼ cup shredded Parmesan
- Preheat oven to 400 degrees F. Spray a 1.5-quart casserole dish with olive oil.
- Using a sharp knife, slice the zucchinis and tomatoes crosswise, ¼-inch thick. If your tomatoes are large, cut each slice in half for easier layering.
- Alternate layers of the tomatoes and zucchini in the baking dish. Sprinkle with the salt, pepper, garlic powder and dried thyme.
- Generously spray the vegetables with olive oil. Sprinkle with the Parmesan.
- Bake the gratin until golden-brown, about 30 minutes. Carefully drain the juices from the bottom and serve.