Summer Squash Gratin

3.9

(12)

15 Reviews

Put abundant summer squash and zucchini to good use in this beautiful gratin with white wine, leeks and Gruyère cheese.

Laura Rege

Updated on May 7, 2024

Tested by

Food & Wine Test Kitchen

Summer Squash Gratin — Photo:
Food & Wine / Photo by Jason Donnelly / Food Styling by Holly Dreesman / Prop Styling by Addelyn Evans

Active Time:

30 mins

Total Time:

1 hr 30 mins

Servings:

In the height of summer, it's hard to ignore the piles of zucchini and squash pouring out of the garden. If you're looking for a way to use them up and create a stunning dish, this is it. Green zucchini, yellow squash, and red tomatoes intertwine beautifully alongside Gruyère cheese, leeks, and white wine in this simple but impressive recipe. A mandoline isn't necessary if you're blessed with impressive knife skills but it does make for perfectly even slices that cook evenly.

Frequently Asked Questions

What is the best dry white wine for cooking?

The best white wines are equally perfect for cooking as they are for drinking however, you don't want to spend too much on a bottle before pouring it into a pan. For this recipe, look for something with good acidity like a Soave or Pinot Grigio.
What is a mandoline?

A mandoline is a kitchen tool used to cut vegetables into thin, even strips or pieces for salads, gratins, and chips.

Notes from the Food & Wine Test Kitchen

Try to pick zucchini and yellow squash that are the same size to make the gratin as even as possible when cooking.

Make ahead

The gratin can be assembled but not baked up to two hours in advance. Refrigerate until ready to bake.

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Ingredients

4 tablespoons extra-virgin olive oil, divided
3 small leeks (1/2 pound), white and tender green parts thinly sliced into rounds
1/4 cup dry white wine
3 medium zucchini, cut lengthwise into 1/8-inch-thick slices, preferably on a mandoline
3 medium yellow summer squash, cut lengthwise into 1/8-inch-thick slices, preferably on a mandoline
Kosher salt
Pepper
1 cup finely shredded Gruyère (about 2 ounces)
1 plum tomato, very thinly sliced crosswise
Flaky sea salt and crusty bread, for serving

Directions

Preheat the oven to 425°F. In a large skillet, heat 1 tablespoon of oil over medium-high heat. Add the leeks and cook, stirring occasionally, until softened, about 3 minutes. Add the wine and cook until evaporated, about 2 minutes. Spread in a 9-inch round baking dish.
Spread the zucchini and yellow squash on 2 large baking sheets. Brush with the remaining 3 tablespoons of oil; season with salt and pepper. Sprinkle with the cheese and let sit until slightly softened, about 5 minutes.
Tightly roll 1 piece of zucchini and set it on the leeks in the center of the dish. Working outward from that center slice, continue rolling and coiling additional pieces of zucchini and yellow squash until you reach the edge of the baking dish. Season the tomato slices with salt and pepper, then tuck in intervals between the zucchini and squash. Scrape any cheese off of the baking sheets and sprinkle on top.
Bake until the zucchini and squash are tender and browned in spots, about 30 minutes. Sprinkle with sea salt. Let cool slightly, then serve with crusty bread.

Originally appeared: July 2017