Zucchini and Spinach Gratin

Grated zucchini and chopped blanched spinach, mixed with onions sautéed with bacon, parsley, and garlic, bound with eggs, topped with grated Parmesan, and baked.

By
Elise Bauer
Elise Bauer
Elise Bauer
Elise founded Simply Recipes in 2003 and led the site until 2019. She has an MA in Food Research from Stanford University.
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Updated February 13, 2023
Elise Bauer
Zucchini Spinach Gratin
Elise Bauer

Another week, another refrigerator drawer filled to the brim with garden zucchini. Sound familiar?

To take a break from our usual (almost daily in the summer) way to cook up the zucchini (see mom's summer squash), we prepared a classic French gratin, with grated zucchini, spinach, onions sautéed with bacon, a persillade of parsley and garlic, all bound together with a few eggs, tossed with Parmesan, and baked until golden brown.

Zucchini has never tasted so good!

I think the bacon might have something to do with it.

And maybe the Parmesan. And the onions, and garlic.

Okay, everything. The combination is perfect.

Zucchini Spinach Gratin
Elise Bauer

The recipe looks more involved than it is. Most of the time is in the baking or in the allowing the zucchini and spinach to drain excess moisture.

The hardest part is grating the zucchini (a breeze if you have a food processor) and the Parmesan. The trick to a successful recipe is squeezing out as much moisture as you can from the zucchini and spinach. Tossing the zucchini with salt and allowing it to drain for half an hour will help draw out a lot of its moisture.

If you don't do this I'm guessing that you might end up with something that is too loose, with too much moisture for the eggs to do their work as a binder.

Best part? The recipe uses two whole pounds of zucchini! Which in our case should use up at least a day or a day and a half's worth of garden produce. Enjoy. ;-)

Zucchini and Spinach Gratin

Prep Time 40 mins
Cook Time 60 mins
Total Time 100 mins
Servings 4 to 6 servings

The recipe calls for bacon and I think it's an important flavor component. For those of you who don't eat pork, or meat, you can substitute butter and or olive oil (a couple tablespoons) to sauté the onions.

If you prefer to use fresh spinach over frozen, use 6 packed cups of fresh chopped spinach leaves, blanched and drained

Ingredients

  • 2 pounds zucchini

  • 1 teaspoon kosher salt

  • 1 pound frozen spinach

  • 3 slices of thick cut bacon (about 3 ounces), cut crosswise 1/4-inch pieces

  • 1 large onion

  • 1 handful of parsley (about 1/2 cup of leaves, lightly packed)

  • 3 cloves garlic, peeled, coarsely chopped

  • 1/2 cup freshly grated Parmesan cheese

  • Freshly ground black pepper

  • 3 large eggs

  • 1 tablespoon extra virgin olive oil

Special Equipment

  • Food processor

Method

  1. Grate and drain the zucchini:

    Grate the zucchini. Toss the grated zucchini with about a teaspoon of Kosher salt. Place the grated zucchini in a large sieve (or colander) placed over a bowl to catch the water as the salt helps the zucchini release its moisture.

    Let sit for 30 minutes or so, then squeeze out the remaining excess moisture with paper towels or a clean tea towel.

    Elise Bauer
    Elise Bauer
  2. Thaw and squeeze the spinach:

    Thaw the spinach, let drain while the zucchini is draining. Then squeeze out the excess moisture with paper towels or a tea towel.

  3. Cook the bacon:

    Heat a large skillet on medium heat. Add the bacon and gently cook until lightly browned and most of the fat rendered out, about 10 minutes.

    Elise Bauer
    Elise Bauer
  4. Add the onions:

    While the bacon is cooking, peel and finely chop the onion. Add the onions to the bacon and cook for an additional 10 minutes, until the onions have softened.

  5. Prepare the parsley and garlic (persillade):

    While the bacon and onions are cooking, prepare the parsley and garlic. Place the parsley and garlic with a small pinch of salt into a food processor and pulse just a couple of times.

    pulse parsley and garlic in a food processor
    Elise Bauer
  6. Preheat the oven to 350°F.
  7. Prepare the filling:

    Place the zucchini into a large bowl. With a wooden spoon, mix in the cooked onions and bacon. Mix in the spinach, parsley, and garlic. Mix in half of the Parmesan. Taste, and add black pepper and more salt to taste. Mix in the eggs.

    filling for spinach zucchini gratin
    Elise Bauer
  8. Fill the gratin pan:

    Coat the bottom and sides of a 2 quart casserole or gratin dish with a tablespoon of olive oil. Put the zucchini spinach mixture into the dish and pack it down. Sprinkle the remaining Parmesan cheese over the top and drizzle with a little olive oil.

    zucchini spinach gratin about to be cooked
    Elise Bauer
  9. Bake:

    Bake in a 350°F oven for 40 to 45 minutes, until the top is nicely browned. Serve immediately. Reheats well.

    zucchini spinach gratin right out of the oven
    Elise Bauer

Inspired by a gratin recipe in Provence: the Beautiful Cookbook.

Nutrition Facts (per serving)
220 Calories
13g Fat
13g Carbs
16g Protein
Show Full Nutrition Label Hide Full Nutrition Label
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Nutrition Facts
Servings: 4 to 6
Amount per serving
Calories 220
% Daily Value*
Total Fat 13g 17%
Saturated Fat 4g 22%
Cholesterol 114mg 38%
Sodium 716mg 31%
Total Carbohydrate 13g 5%
Dietary Fiber 5g 18%
Total Sugars 4g
Protein 16g
Vitamin C 29mg 147%
Calcium 246mg 19%
Iron 3mg 17%
Potassium 823mg 18%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
Nutrition information is calculated using an ingredient database and should be considered an estimate. In cases where multiple ingredient alternatives are given, the first listed is calculated for nutrition. Garnishes and optional ingredients are not included.