Zucchini, Eggplant, Tomato Gratin

Summer zucchini, eggplant, and tomatoes, beautifully presented in a baked casserole gratin. A French tian!

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Photography Credit: Elise Bauer

Oh my. Look who’s getting all fancy with the vegetables!

It’s as if my garden decided to throw a prom, and the eggplants, zucchini, and tomatoes banded together to show everyone else up. (Clearly they deserve best prize for something, don’t you think?)

Normally I would look at something like this and think it’s waaaay too complicated. But this summer vegetable gratin is actually quite straightforward.

To prepare these vegetables, you have to cut them anyway, so why not cut them in rounds and arrange them in a pretty pattern?

Zucchini Eggplant Tomato Gratin

If you recall, Remy, the “little chef” in Pixar’s Ratatouille movie, prepared something similar for Anton Ego, the food critic. This isn’t that dish, but something much easier.

You just sauté onions and bell peppers, layer them at the bottom of a casserole dish, top with rounds of eggplant, zucchini, and tomato. Top that with cheese and bake!

It’s a lovely, easy, colorful presentation for our favorite summer vegetables. A perfect side to take to a party.

Zucchini, Eggplant, Tomato Gratin Recipe

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  • Prep time: 20 minutes
  • Cook time: 1 hour, 10 minutes
  • Yield: Serves 6 to 8

We're topping this gratin with provolone and Parmesan cheeses. You could easily top it with Gruyere instead. For a more Provencal approach, skip the cheese all together and top with bread crumbs, minced garlic, parsley, and olive oil.

Ingredients

  • 3 Tbsp olive oil
  • 2 cups sliced yellow onion (1 large onion)
  • 1 cup of sliced red, orange, or yellow bell peppers
  • 1 long eggplant (a slender eggplant like a Japanese eggplant, not a large globe, about 1/2 pound)
  • 1 large zucchini (about 10 to 12 inches long, 1 1/2 inch diameter, about 1/2 pound), or other summer squash
  • 2 medium sized tomatoes
  • 3 cloves of garlic, peeled and smashed
  • 1 1/2 teaspoons salt
  • 2 Tbsp chopped fresh parsley
  • 2 ounces Provolone cheese, sliced or grated
  • 3 Tbsp grated Parmesan cheese

Method

1 Sauté the onions and peppers: In a large sauté pan heat 2 Tbsp of the olive oil on medium high heat. Add the sliced onions and cook until lightly browned, stirring frequently, about 10 minutes.

Add the sliced bell peppers and continue to cook with the onions until the bell peppers are softened and the onions are well browned, about 5 to 6 minutes more.

When done, transfer the onions and bell peppers into a large gratin pan or casserole dish.

2 Slice the eggplant, zucchini, and tomato in similar sized rounds: While the onions and peppers are cooking, slice the eggplant and zucchini in 1/4-inch thick round slices.

You'll also want to slice the tomato into 1/4-inch thick slices, but depending on how big your tomato is, you may need to cut the tomato in half or in quarters first.

All of the sliced vegetable pieces should be about the same size to make it easier to layer them in an attractive manner.

3 Layer the eggplant, zucchini, tomato rounds on top of the onions, bell peppers as garlic: Preheat the oven to 350°F (175°C). Spread the cooked onions and bell peppers in an even layer at the bottom of the gratin dish. Place the mashed garlic on top of the onions and peppers.

Arrange the slices of the eggplant, zucchini, and tomato on top of the cooked onions and peppers, alternating the vegetables, in an attractive pattern, stacking them and fanning them across the surface of the dish.

4 Top with salt, parsley, cheeses, olive oil: Sprinkle with salt and parsley. Top with Provolone and Parmesan cheeses.

Drizzle the remaining tablespoon of olive oil around the perimeter, where the vegetables meet the side of the dish.

5 Cover with foil and bake, broil uncovered to finish: Cover with foil (it helps to grease the underside of the foil with a little olive oil so that the cheese as it melts does not stick to the foil).

Bake for 40 minutes at 350°F (175°C). Remove the foil. Turn on the broiler and broil for 5 minutes or until nicely browned.

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Zucchini Eggplant Tomato Gratin

Showing 4 of 33 Comments

  • Renee McGowan

    At my son’s house sitting with my grandkids, I noticed, too late, that there was no meat thawed out. I found zucchini and eggplant in the fridge, then found your recipe. I used what was at hand. No provolone. No peppers. No oregano. I used parmesan and 3 different cheddar cheeses. Also, I used cauliflower instead of peppers just for volume. As I was putting the cheese on top, it occurred to me that I forgot the tomatoes, which were fire roasted Italian spiced diced tomatoes from a can for lack of fresh tomatoes. So, they went on top. Also, the eggplant I had diced already to make it go further as I am serving it as a main dish. It’s in the oven right now. Photos forthcoming. It smells wonderful in here!!!

  • Joan Jones

    I added a bottom layer of ground turkey mixed with quinoa and it made a delicious main dish. My husband recently had a heart attack and I learned that eggplant is a great food for cleaning arteries. This was the first eggplant recipe I’ve ever tried and we loved it!

  • Charles H Rooney Jr

    Do you use smoked Provolone cheese or aged Provolone cheese?

  • FrannyD

    Well this is one delicious dish. I’ve made it several times now with different variations. The zucchini, eggplant and tomato remains the same. Ive sautéed the garlic with the onions and peppers. I’ve doubled it. Changed up the cheese. This time I’ve added feta cheese, fresh basil and parsley. And Italian breadcrumbs mixed with a little olive oil. Panko works great too! Always rave reviews. Great side dish, or a main for the vegetarian .

  • Josie

    Tonight was the second time I made this and it turned out just as delicious as the first time! I used fresh veggies from the garden, plus mixed some bread crumbs, minced fresh basil, thyme and oregano, and shredded Italian cheese mix and sprinkled it over the top before baking. I didn’t use quite as much salt and it was plenty salty. I really like how this cooking method makes the zucchini and eggplant perfectly tender without being soggy or oily. And the dish is really simple! Thanks for the recipe!

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