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Yields:
6 - 8 serving(s)
Prep Time:
35 mins
Total Time:
1 hr 20 mins
Zucchini has a way of taking over by the end of summer, but this cheesy zucchini gratin is one recipe you'll be happy to make on repeat all year long. Tender rounds of zucchini are layered with a rich gruyère cream sauce flavored with garlic, shallots, Dijon, thyme, and a hint of nutmeg, then topped with buttery Parmesan panko for an irresistibly crisp, golden finish. It's an easy side dish that feels a little elegant, pairing just as well with a holiday ham or roast turkey as it does with a simple roast chicken or grilled steak. And because zucchini is available year-round, there's no reason to save this comforting casserole for summer.
How do you keep zucchini gratin from getting watery?
Because zucchini is naturally full of moisture, it can easily make a gratin watery if it's not prepared properly. This recipe avoids that with a few simple techniques. The zucchini is cooked in a skillet before baking so it can release much of its moisture up front. It's then lifted into the baking dish with a slotted spoon, leaving any accumulated liquid in the pan. The cheese sauce is also made on the thick side, so as the zucchini gives off a little more moisture in the oven, the sauce becomes perfectly creamy instead of thin. Together, these steps create a gratin that's rich, cohesive, and never soupy.
Does zucchini gratin freeze well?
Zucchini gratin is best enjoyed fresh, but it can be stored in the refrigerator for up to 4 days. Freezing this dish is not recommended, as the zucchini's high water content (even when reduced by precooking) combined with the creamy sauce can lead to a soggy texture when thawed and reheated. For the best results, prepare and enjoy zucchini gratin within a few days of making it. If you are looking for a cheesy baked zucchini dish to stow in the freezer, consider making zucchini lasagna instead.
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Ingredients
- 1/2 cup (1 stick) salted butter, plus more for the baking dish
- 1/2 cup panko breadcrumbs
- 1/4 cup grated parmesan cheese (about 1 oz.)
- 4 medium zucchini, sliced into 1/4-inch rounds (about 2 1/4 lb.)
- 1 1/2 tsp. kosher salt
- 3 garlic cloves, finely chopped
- 2 shallots, finely chopped
- 2 Tbsp. all-purpose flour
- 1/2 tsp. black pepper
- 1 1/2 cups milk, at room temperature
- 1 cup shredded gruyère (about 4 oz.)
- 1 Tbsp. dijon mustard
- 2 tsp. fresh thyme leaves, chopped, plus more for serving
- 1/4 tsp. freshly grated nutmeg
Directions
- Step 1Preheat the oven to 400°F. Butter a 2-quart baking dish.
- Step 2In a medium bowl, combine the panko and parmesan. In a large skillet with a lid, melt 2 tablespoons of the butter over medium heat. Pour the melted butter over the breadcrumbs and toss to coat.
- Step 3In the same skillet, melt 2 tablespoons butter over medium heat. Add the zucchini and 1 teaspoon salt, cover, and cook until the zucchini releases its liquid, about 10 minutes, stirring once halfway through cooking. Uncover and stir until the liquid evaporates, about 5 more minutes. Remove the zucchini to a large bowl. Wipe out the skillet.
- Step 4In the same skillet, melt the remaining 4 tablespoons of butter over medium heat. Add the garlic, shallots, and remaining ½ teaspoon salt and cook until softened, 1 to 2 minutes. Stir in the flour and pepper and cook, stirring, until the raw flour smell disappears, 1 to 2 minutes. Gradually whisk in the milk, whisking until no lumps remain. Cook, scraping the bottom of the skillet with a rubber spatula, until the sauce thickens slightly, 2 to 3 minutes. Remove from heat and stir in the gruyère, mustard, thyme, and nutmeg.
- Step 5Use a slotted spoon to scoop half the zucchini into the prepared baking dish, leaving behind any liquid. Pat into an even layer, then pour over half the cheese sauce. Add the remaining zucchini and top with the remaining sauce. Sprinkle with the panko mixture and bake until golden brown and bubbling, 30 to 35 minutes.
- Step 6Let the gratin sit 5 minutes to cool slightly before sprinkling with more thyme and serving.
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