Extra-Creamy Zucchini and Squash Casserole

published Aug 15, 2021
Zucchini and Squash Casserole

In this recipe, very simple ingredients come together in the oven to create an irresistible dish more delicious than the sum of its parts.

Serves6 to 8

Prep45 minutes

Cook40 minutes

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Zucchini and squash casserole in a dish with a gold handle
Credit: Laura Rege

Explore the cozy side of zucchini and yellow squash by baking a cheesy, hearty casserole. This recipe is the perfect early fall dish: Squash is still in peak season, but the weather has begun to cool down a bit (enough to entertain the idea of using your oven again!).

There are many variations of zucchini casserole, many of which are cream-based. But we upped the ante with a rich béchamel sauce made from whole milk, butter, and flour. Not only does it add some extra decadence, but it’s also much less likely to separate when it combines with the juices from the zucchini. 

How Do You Keep Zucchini Squash Casserole from Getting Watery?

  • Option #1: Toss squash generously with salt and set in a colander over a bowl (or in the sink) to let the water drain out for about 20 minutes. Then use your hands, a clean kitchen towel, or paper towels to squeeze more moisture out. Don’t be shy about using a little strength — the squash will stay together. (It’s what we do here and what we generally prefer.)
  • Option #2: Cook the squash to allow excess water to evaporate. This can be done in the oven or a skillet, but it takes a bit more time.

How Do You Prevent Overcooking Zucchini and Squash?

Squash doesn’t overcook as easily as you think. This casserole has a stewing effect on the squash. And rest assured: The cheese will bubble and the breadcrumbs will turn golden-brown before you get anywhere close to overcooking the squash.

Credit: Laura Rege

What Cheese Is Best for the Casserole?

For the bulk of the cheese, we love a gooey, melty cheese like fontina paired with Parmesan. You could also try a nutty Gruyère, mild mozzarella, or nice sharp cheddar. A crumbled goat cheese would be delicious as well, albeit not as melty. Really, you can’t go wrong.

Zucchini and Squash Casserole

In this recipe, very simple ingredients come together in the oven to create an irresistible dish more delicious than the sum of its parts.

Prep time 45 minutes

Cook time 40 minutes

Serves 6 to 8

Nutritional Info


  • 4 1/2 tablespoons

    unsalted butter, divided

  • 1 1/2 pounds

    zucchini (about 3 large)

  • 1 1/2 pounds

    yellow summer squash (about 3 large)

  • 1 3/4 teaspoons

    kosher salt, divided, plus more for the topping

  • 4 cloves


  • 1/4 cup

    all-purpose flour

  • 3 cups

    whole milk

  • 1/2 teaspoon


  • 1/4 teaspoon

    dry mustard

  • 1/4 teaspoon

    freshly ground black pepper, plus more for the topping

  • 8 ounces

    fontina cheese, shredded (about 2 cups)

  • 1/2 cup

    panko breadcrumbs

  • 1/2 ounce

    Parmesan cheese, grated (about 1/4 cup)

  • 2 teaspoons

    olive oil


  1. Place 1/2 tablespoon of the unsalted butter in an 8x11-inch or other 2-quart baking dish and set aside to let the butter come to room temperature. Using a mandoline or chef's knife, trim and very thinly slice 1 1/2 pounds zucchini and 1 1/2 pounds yellow summer squash crosswise. Place in a colander, sprinkle with 1 1/2 teaspoons of the kosher salt, and toss to combine. Place the colander in the sink or over a large bowl and let the squash drain for 20 minutes. Meanwhile, heat the oven and make the béchamel sauce.

  2. Arrange a rack in the middle of the oven and heat the oven to 350ºF. Finely chop 4 garlic cloves. Melt the remaining 4 tablespoons unsalted butter in a medium saucepan over medium heat. Add the garlic and cook, stirring occasionally, until fragrant, about 1 minute. Add 1/4 cup all-purpose flour and cook, whisking, until the garlic and flour are lightly toasted, about 2 minutes.

  3. While whisking constantly, slowly pour in the 3 cups milk. Increase the heat to medium-high and bring to a boil, stirring constantly. Reduce the heat to maintain a simmer and cook, whisking often, until the sauce thickens significantly, 5 to 10 minutes. Remove from the heat. Add 1/2 teaspoon paprika, 1/4 teaspoon dry mustard, the remaining 1/4 teaspoon kosher salt, and 1/4 teaspoon black pepper, and whisk to combine.

  4. When the squash is ready, working with a heaping handful at a time, place in a clean kitchen towel or paper towels and squeeze as much water as possible from the squash, then place in a bowl. Shred 8 ounces fontina cheese on the large holes of a box grater.

  5. Coat the baking dish with the softened butter. Spread 1/2 cup of the béchamel sauce in the bottom of the baking dish. Spread half of the squash over the cream sauce in an even layer. Drizzle with half of the remaining béchamel sauce (about 1 cup), then sprinkle with half of the fontina. Layer on the remaining squash, béchamel sauce, and fontina.

  6. Place 1/2 cup panko breadcrumbs, 1/4 cup grated Parmesan cheese, and 2 teaspoons olive oil in a small bowl, season with a pinch of kosher salt and black pepper, and stir to combine. Sprinkle evenly over the casserole.

  7. Bake until the sides of the casserole are bubbling, about 40 minutes. Check after 30 minutes and tent the casserole loosely with aluminum foil it the top is already browned before continuing baking. Let rest for 15 minutes before serving.

Recipe Notes

Storage: Leftovers can be refrigerated in an airtight container for up to 5 days.