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Easy Cheesy Zucchini Gratin Recipe

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★★★★★

4.7 from 50 reviews

Cheesy Zucchini Gratin is a creamy, savory baked side dish that transforms tender zucchini into a rich and comforting casserole. Featuring a smooth cream sauce blended with mozzarella, cheddar, and Parmesan cheeses, and crowned with a golden, crisp panko and Parmesan topping, this gratin balances delicate vegetable flavors with luscious richness. Perfect for family dinners, holiday meals, or anytime you want to elevate zucchini, this dish is both elegant and approachable, making it a versatile crowd-pleaser.

Ingredients

Scale

Zucchini Preparation

  • 2 pounds zucchini, sliced into 1/4-inch rounds
  • 1 teaspoon salt, divided

Cream Sauce

  • 2 tablespoons unsalted butter
  • 1 small yellow onion, finely diced
  • 3 cloves garlic, minced
  • 1 tablespoon all-purpose flour
  • 1 cup heavy cream
  • 1/2 cup whole milk
  • 1/2 teaspoon black pepper
  • 1/4 teaspoon ground nutmeg
  • 1 teaspoon dried thyme or 1 tablespoon fresh thyme leaves

Cheeses and Topping

  • 1 cup shredded mozzarella cheese
  • 1/2 cup shredded sharp cheddar cheese
  • 1/2 cup grated Parmesan cheese, divided
  • 1/2 cup panko breadcrumbs
  • 1 tablespoon olive oil

Garnish

  • 2 tablespoons chopped fresh parsley

Instructions

  1. Prepare the zucchini: Preheat the oven to 375°F and lightly grease a 9 x 13-inch baking dish. Place the sliced zucchini in a large bowl and sprinkle with 1/2 teaspoon of salt. Toss well, then spread the zucchini slices over paper towels or clean kitchen towels. Let them rest for 20 to 30 minutes to draw out moisture. After resting, pat the zucchini thoroughly dry.
  2. Make the cream sauce: In a large skillet over medium heat, melt the butter. Add the finely diced onion and cook for 4 to 5 minutes, stirring frequently, until softened. Add the minced garlic and cook for 30 seconds until fragrant. Sprinkle in the flour and stir continuously for about 1 minute to cook out the raw flavor. Gradually pour in the heavy cream and whole milk while whisking constantly until the mixture is smooth. Add the remaining 1/2 teaspoon salt, black pepper, ground nutmeg, and thyme. Allow the sauce to simmer gently for 2 to 3 minutes until it slightly thickens. Remove from heat and stir in the mozzarella, cheddar, and 1/4 cup Parmesan cheese until fully melted and creamy.
  3. Assemble the gratin: Spread half of the dried zucchini slices evenly in the prepared baking dish. Spoon half of the cheese cream sauce over the zucchini. Layer the remaining zucchini slices on top and pour over the remaining sauce. In a small bowl, combine the panko breadcrumbs, olive oil, and remaining 1/4 cup Parmesan cheese. Sprinkle this bread crumb mixture evenly over the top of the assembled gratin.
  4. Bake until golden: Place the dish in the preheated oven and bake uncovered for 30 to 35 minutes, or until the gratin is bubbling at the edges and the top is a golden brown color. If desired, broil for an additional 1 to 2 minutes at the end to enhance browning, watching carefully to prevent burning.
  5. Rest and garnish: Remove the gratin from the oven and let it rest for 10 minutes to allow the sauce to set slightly. Just before serving, sprinkle the top with chopped fresh parsley for a burst of color and freshness.

Notes

  • Salting and drying the zucchini is essential to prevent excess moisture and ensure a creamy, rich gratin without sogginess.
  • Freshly shred cheese when possible for smoother melting and better texture than pre-shredded cheese.
  • If the cream sauce is too thin, simmer a little longer to thicken; if too thick, add a splash of milk to loosen it.
  • To make the breadcrumb topping extra crispy, substitute 1 tablespoon of melted butter for the olive oil.
  • The dish can be assembled ahead without the topping and refrigerated for up to 24 hours before baking.
  • Leftovers keep well in the refrigerator for up to 3 days and reheat beautifully in the oven to maintain topping crispness.
  • Variations include swapping cheddar for Gruyère or Monterey Jack cheese, adding yellow squash or baby spinach, or mixing sautéed mushrooms into the sauce.

Keywords: zucchini gratin, cheesy zucchini casserole, baked zucchini side dish, creamy zucchini gratin, vegetable gratin

Find it online: https://lucabites.com/easy-cheesy-zucchini-gratin-recipe/