Zucchini Au Gratin is the perfect blend of comfort and freshness. Thinly sliced zucchini, baked until tender with a golden, cheesy topping. It’s creamy, crispy, and packed with flavor in every bite—a simple yet satisfying side dish!
Zucchini Au Gratin has become my go-to side dish when I want something comforting but still kind of healthy. The zucchini gets super tender, and the cheesy, crispy top is impossible to resist. It's one of those dishes that feels fancy but is actually super easy to throw together!
Please leave us a comment or rating below to let us know what you think of the recipe!
Try some of our other favorite side dishes: Southern Squash Casserole, Cheesy Hash Brown Casserole, Zucchini Tomato Bake, or Italian Grinder Pasta Salad.
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What ingredients are needed for Zucchini Au Gratin?
- zucchini
- parmesan cheese
- cheddar cheese
- mozzarella cheese
- onion
- butter
- heavy cream or milk
- all purpose flour
- salt
- pepper
- garlic
FAQs
Zucchini au gratin is a baked dish where thinly sliced zucchini is layered in a creamy sauce, typically topped with cheese and breadcrumbs, then baked until golden and bubbly.
Absolutely! While most recipes call for Parmesan or Gruyère, you can use cheddar, mozzarella, or even a mix of cheeses for extra flavor.
No need! Just wash the zucchini well and slice them thin. The peel helps hold the slices together and adds a bit of texture.
Zucchini is naturally high in water. To avoid a soggy gratin, sprinkle the zucchini slices with salt and let them sit for 10–15 minutes. This draws out moisture, which you can pat dry before baking.
Yes! You can assemble the gratin a day ahead, refrigerate it, and then bake it just before serving. It might need a few extra minutes in the oven if it’s cold from the fridge.
Top Tips
- Use a mandoline: For thin, even zucchini slices, a mandoline is a lifesaver. Consistent slices cook evenly and create that perfect layered look.
- Add a crunchy topping: For extra texture, mix breadcrumbs with a bit of butter or olive oil and sprinkle it on top before baking.
- Herb it up: Fresh thyme, rosemary, or basil can add a wonderful aroma and enhance the overall flavor of the dish.
- Let It Rest: Allow the gratin to cool for a few minutes before serving. This helps it set up a bit and makes it easier to slice.
- Refrigerate: Transfer the leftovers to an airtight container or cover the baking dish tightly with plastic wrap or foil. It will keep in the fridge for 3 to 4 days.
- Freezing: If you want to freeze it, let the dish cool completely and wrap it tightly in plastic wrap, followed by aluminum foil, or use a freezer-safe container. It can be stored in the freezer for up to 3 months.
How to make Zucchini Au Gratin
- Preheat your oven to 400°F (200°C). Grease a 9x13" baking dish with butter or nonstick spray.
- Melt 4 tablespoons of butter in a large saucepan. Add minced garlic and diced onion, until onion is translucent. Combine zucchini into the pan for about 10-15 minutes, or until tender.
- Mix in salt, pepper, and parmesan cheese. Cook for 5 minutes.
- In a small bowl or measuring cup, whisk flour into heavy cream/milk until smooth. Add to the zucchini in the saucepan, heat to bubbling. Cook on low until thickened.
- Pour the zucchini mixture into prepared baking dish. Sprinkle shredded cheese over the top. Bake 12-15 minutes in the preheated oven. Allow to rest 5-10 minutes before serving. Enjoy!
Zucchini Au Gratin
Ingredients
- 6 zucchini, thinly sliced
- 4 tablespoon unsalted butter
- ½ yellow onion, diced or thinly sliced
- 1 teaspoon garlic cloves, minced
- 2 tablespoon all purpose flour
- 1 cup heavy cream or milk
- 1 teaspoon salt
- ½ teaspoon black pepper
- ½ cup parmesan cheese
- 1 cup mozzarella cheese, shredded
- ½ cup cheddar cheese, shredded
Instructions
- Preheat your oven to 400°F (200°C). Grease a 9x13" baking dish with butter or nonstick spray.
- Melt 4 tablespoons of butter in a large saucepan. Add minced garlic and diced onion, until onion is translucent. Combine zucchini into the pan for about 10-15 minutes, or until tender.
- Mix in salt, pepper, and parmesan cheese. Cook for 5 minutes.
- In a small bowl or measuring cup, whisk flour into heavy cream/milk until smooth. Add to the zucchini in the saucepan, heat to bubbling. Cook on low until thickened.
- Pour the zucchini mixture into prepared baking dish. Sprinkle shredded cheese over the top. Bake 12-15 minutes in the preheated oven. Allow to rest 5-10 minutes before serving. Enjoy!
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