zucchini gratin recipe

Zucchini Gratin Recipe

When the garden is mass-producing zucchini in mid-summer, look no further than this delicious zucchini gratin recipe to make good use of it.

zucchini gratin recipe

Zucchini Gratin Recipe

Prep Time 1 hour 5 minutes
Cook Time 1 hour
Total Time 2 hours 5 minutes
Course Side Dish
Servings 6 servings
Calories 202 kcal


  • 6 Tablespoons extra virgin olive oil
  • 2 lbs. zucchini sliced into ¼ inch thick rounds
  • 2 teaspoons sea salt
  • 2 medium onions peeled, halved, and sliced thin
  • 1 teaspoon freshly ground black pepper
  • 2 plump garlic cloves minced
  • 1 tablespoon minced fresh thyme leaves -or- ½ teaspoon dried thyme
  • 1 - 2 slices of bread
  • 1 cup grated Parmesano-Reggiano or Romano cheese or a combination of the two
  • ¼ cup chopped chives
  • 10 fresh basil leaves chopped (optional)


  • Toss zucchini slices with one teaspoon of the salt and place in a colander to drain for about an hour.
  • Place slices of drained zucchini on several layers of paper towels, cover with several more layers of paper towels and press to squeeze out as much liquid as possible.
  • Place oven rack in upper-middle position and pre-heat oven to 400º F. Coat a 13” x 9” baking dish with olive oil.
  • While the oven is preheating, saute the onions over medium heat in one Tablespoon of olive oil, ½ teaspoon salt, and ½ teaspoon black pepper until golden brown - about 20 to 25 minutes.
  • Combine 3 Tablespoons olive oil, minced garlic, ½ teaspoon black pepper and thyme in a large bowl and toss with the zucchini.
  • Arrange a layer of zucchini slices in the baking dish, then cover with the onions, repeat layer with the remaining zucchini slices.
  • Bake uncovered until vegetables are tender and edges begin to brown - about 40 to 45 minutes.
  • While the zucchini bakes, process the bread in a food processor to make crumbs. Add in a tablespoon of olive oil, the cheese and the chives. Pulse a few more times to combine.
  • After the zucchini bakes, remove it from the oven, increase the the temperature to 450º F, and sprinkle the bread crumb topping over the zucchini.
  • Bake until the topping is lightly browned — about 5 to 10 minutes. Remove dish from oven, sprinkle with basil (if using) and let sit at room temperature for 10 minutes before serving.


Any kind of sliceable, long squash can be used in this recipe: it's just fine to use yellow squash or a mixture of squash types. Shallots or scallions can be substituted for the chives.


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