Ratatouille Gratin
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Ratatouille gratin turns the classic Provençal ratatouille vegetables — eggplant, zucchini, summer squash, and tomatoes — into an elegant, oven-baked gratin with a browned cheese and breadcrumb topping. Layers of thinly sliced vegetables create a beautiful spiral pattern, and a golden crust adds texture to this vibrant side dish that’s perfect for dinner parties or weeknight meals alike. Rather than tossing the vegetables in a creamy bechamel sauce, I lighten up the recipe with sautéed onions in olive oil as the base.
If you love Mediterranean vegetable dishes like this, be sure to try my grilled vegetable pasta salad or this hearty Moroccan vegetable stew next. You can also try this version as a ratatouille pasta.
Why You’ll Love This Recipe
- Beautiful & impressive – A spiral of colorful vegetables makes a stunning presentation.
- Light but satisfying – Sautéed onions and simple seasonings let the fresh produce shine.
- Crispy cheesy topping – Crisp breadcrumbs and a blend of Gruyère and Parmesan add savory crunch.
What is Gratin?
A French dish with a crust of browned breadcrumbs or melted cheese typically prepared in a shallow dish. Gratins are frequently made with potatoes like this recipe, though it can be made with other vegetables as well. For a more unique twist try it with Brussels sprouts.
Key Ingredients in This Recipe
- Eggplant – I recommend either using Chinese eggplants or graffiti eggplants because they are thinner and longer, therefore more similar to the size of the zucchini, yellow squash and tomatoes, which makes it easier to layer the vegetables.
- Zucchini – When available I buy my zucchini at the local farmers market. Look for firm zucchini with unblemished skin.
- Yellow squash – When buying yellow squash, look at the stem. It should be intact and the squash should feel for its size. Yellow squash will have a more bulb shaped base and thinner stem.
- Tomatoes – Roma tomatoes have a thicker skin and lower water content than many other tomato varieties, making it perfect for this since, as they cook, they won’t water the dish down and there’s no need to peel them first. They add just enough moisture and color to complement the other ingredients in this dish. Roma tomatoes are available year-round though tomatoes are at their peak in the summer months.
A full ingredient list with exact amounts can be found in the recipe card below.
Pro Tip
Lightly salt the sliced vegetables and let them sit for 10–15 minutes before assembling. Pat them dry to draw out excess moisture, which helps the gratin bake up tender with a crisp, golden topping instead of watery.
Swaps and Substitutions
- Eggplant: Replace with thinly sliced sweet potatoes or bell peppers for variation.
- Gruyère cheese: Swap with mozzarella or Fontina if you prefer a milder cheese.
- Parmesan cheese: Pecorino Romano or Asiago offers a sharper finish.
- Breadcrumbs: Use panko for extra crunch or gluten-free breadcrumbs if needed.
- Herbs: Add fresh basil or oregano for additional Mediterranean flavor.
How to Make Ratatouille Gratin (Step-by-Step)
Heat a 12” (30cm) heat proof baking dish over medium heat, add the olive oil and heat through. Add the garlic and thyme and sauté until fragrant and the garlic is golden, about 1 minute. Use tongs to remove the garlic and thyme and discard. (See tips and tricks section for instructions if you are using a glass or ceramic baking dish).
Return the pan with the infused oil to heat. Add the onion and sauté, stirring occasionally, until tender, about 8 minutes.
Preheat the oven to 400ºF (200ºC). Add the onions to the bottom of a 12-inch oval ceramic dish. Alternate the slices of eggplant, zucchini, summer squash and tomato slices in the baking dish in a spiral formation. Season with salt.
Heat a medium non-stick sauté pan over medium heat, add the butter and allow to melt. Add the breadcrumbs and sauté, stirring frequently, until the breadcrumbs are golden brown, about 5 minutes.
Sprinkle the Gruyere and Parmesan cheese over the vegetables and top with the breadcrumbs.
Bake until the top is golden brown and the vegetables are tender, about 20 to 25 minutes.
How to Serve Ratatouille Gratin
- As a side dish: Serve warm alongside roasted chicken, grilled fish, or steak.
- Vegetarian main: Pair with crusty bread and a green salad for a light dinner.
- With grains: Spoon over quinoa or rice for a heartier meal.
- Family-style platter: Bring to the table in the baking dish for shared serving.
How to Store Ratatouille Gratin
- Refrigerate: Store leftovers in an airtight container for up to 3–4 days.
- Reheat: Warm in a 350°F oven until heated through to maintain texture.
- Avoid sogginess: Re-crisp the topping under the broiler for a minute if needed.
- Make ahead: Assemble and refrigerate before baking; bake just before serving.
FAQ – Frequently Asked Questions
Yes. Assemble the gratin and refrigerate before baking, then bake just before serving for the best texture.
Eggplant, zucchini, summer squash, and Roma tomatoes provide the right balance of flavor and texture.
Yes. This recipe is naturally vegetarian and works well as either a side dish or a meatless main.
Absolutely. Fresh basil, rosemary, or thyme enhance the Mediterranean flavor profile.
Using Roma tomatoes and evenly sliced vegetables helps control excess moisture during baking.
Other Recipes to Try
If you loved preparing this French-inspired ratatouille gratin, I recommend checking out some of these recipes:
Tried it? Loved it? Tweaked it? Leave a review below and tell me how it went – I’m all ears (and always hungry).
Ratatouille Gratin
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Ingredients:
- ¼ cup extra-virgin olive oil
- 2 sprigs fresh thyme
- 2 cloves garlic, smashed
- ½ medium yellow onion, diced
- 3 medium Chinese or graffiti eggplants, thinly sliced
- 2 large zucchini, thinly sliced
- 2 large summer squash, thinly sliced
- 4 medium Roma tomatoes, thinly sliced
- Kosher salt, as needed
- 3 tablespoons unsalted butter
- ½ cup plain breadcrumbs
- ¼ cup shredded Gruyere cheese
- ¼ cup grated Parmesan cheese
Instructions:
- Heat a 12” (30cm) metal or cast iron baking dish over medium heat, add the olive oil and heat through. (See instructions above if you are using a glass or ceramic baking dish). Add the garlic and thyme and sauté until fragrant and the garlic is golden, about 1 minute. Use tongs to remove the garlic and thyme and discard.
- Return the pan with the infused oil to heat. Add the onion and sauté, stirring occasionally, until tender, about 8 minutes.
- Preheat the oven to 400ºF (200ºC).
- Add the onions to the bottom of a 12-inch oval ceramic dish. Alternate the slices of eggplant, zucchini, summer squash and tomato slices in the baking dish in a spiral formation. Season with salt.
- Heat a medium non-stick sauté pan over medium heat, add the butter and allow to melt. Add the breadcrumbs and sauté, stirring frequently, until the breadcrumbs are golden brown, about 5 minutes.
- Sprinkle the Gruyere and Parmesan cheese over the vegetables and top with the breadcrumbs.
- Bake until the top is golden brown and the vegetables are tender, about 20 to 25 minutes.
Notes:
Nutrition:
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