A gratin is a dish topped with a golden browned crust of breadcrumbs and/or melted cheese. In France, gratins are generally made with potatoes. This Easy Make Ahead Zucchini Gratin is an amazing deviation that will have you coming back for more!
What do you make when you have fresh zucchini that needs to be used - Easy Cheesy Make Ahead Zucchini Gratin is the answer! Throughout dinner, the Master Taste Tester kept commenting on how good it was - the ultimate compliment! It will soon become your family favorite.
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Why You'll Love This Recipe
- Convenience: This recipe is simple to make. Also, because you can assemble this dish ahead of time, it is perfect for a busy schedule.
- Deliciously Creamy and Cheesy: In this recipe, grated zucchini is combined with a creamy bechamel sauce and topped with gruyere cheese for cheesy goodness.
- Delicate Zucchini Flavor: The subtle sweetness of the zucchini perfectly complements the richness of the cheese and creamy sauce. Also, zucchini is a healthy vegetable that provides vitamins and fiber.
- Versatile Side Dish with Elegant Presentation: This dish pairs well with various entrees and looks impressive when served at dinner parties or potlucks.
Ingredients - Here's What You'll Need for this Zucchini Casserole Recipe
This zucchini recipe uses simple ingredients to produce the perfect side dish.
- Vegetables: You can't have zucchini gratin without zucchini! I use fresh zucchini that is medium to small in size. Onions are added for flavor.
- Bechamel Sauce: Bechamel is a standard sauce made with unsalted butter, all-purpose flour, and milk, seasoned with Kosher salt, black pepper, and freshly grated nutmeg.
- Cheesy Goodness: The gruyere cheese in this recipe perfectly complements the other ingredients. You could also use Swiss cheese.
- Crunchy Topping: I'm a huge fan of crunchy toppings for my casseroles, and Panko breadcrumbs fit the bill!
Simple Steps for an Impressive Dish
- I combined the gruyere cheese and panko breadcrumbs for the cheesy, crunchy topping. Sometimes, I will add some freshly grated parmesan cheese to the topping mixture.
- Next, I used my food processor to grate the zucchini and the onion.
- I transferred the grated zucchini and onion to a wire mesh strainer set over a bowl and sprinkled on some salt. The idea was to remove as much liquid as possible from the zucchini and the onions.
- After 30 minutes, I squeezed liquid from the zucchini and onion with my hands. Then, I placed the grated zucchini and onion in a paper towel and continued squeezing as much liquid as possible.
I was amazed that I ended up with about a cup of liquid! This is significant because the dish would have otherwise been incredibly watery had the liquid not been removed!
- I heated unsalted butter in a 12-inch skillet over medium heat until it was foaming. Then, I added the squeezed zucchini and onion and cooked them for about 5 minutes until they were just tender.
- After that, I added the remaining salt, pepper, nutmeg, and flour and stirred the mixture to combine everything.
- After about a minute, I added the milk and stirred the mixture until it was thickened and bubbly.
- I transferred the zucchini mixture to a casserole dish sprayed with non-stick spray. Then, I topped it with the Gruyère/Panko mixture and dotted the zucchini gratin with some additional unsalted butter.
At this point, I could have refrigerated the covered zucchini gratin for later use.
Instead, I popped the zucchini gratin into a preheated 400°F oven for about 20 minutes. After 20 minutes, it was bubbling hot, golden brown, and absolutely delicious. Yum!
Frequently Asked Questions
The zucchini and onion can be grated using the largest holes in a box grater if you don't have a food processor.
I happened to have fresh nutmeg, so I used it. I could have also used ground nutmeg.
Zucchini is a summer squash that is actually a fruit. It's grown throughout the US during the warm summer months. While you may think of zucchini as a vegetable, it is actually a fruit. Zucchini is low in calories and a good source of vitamins A and C, fiber, and potassium.
Courgette is another name for zucchini.
You can substitute Swiss cheese, Cheddar cheese, Monterey Jack, and Fontina cheese for the Gruyère cheese.
Plain breadcrumbs can be easily substituted for the Panko breadcrumbs. The topping will not be quite as crispy, though.
This Easy Make-Ahead Zucchini Gratin makes excellent leftovers. If you want the cheese/panko topping to be crisp, you should reheat it in a 350°F oven for about 15 minutes or until heated through.
You can make this amazing casserole several hours to a day before baking it. Cover it with aluminum foil and refrigerate. Add about 5 minutes to the baking time if baking it from the refrigerator.
Other Delicious Zucchini Recipes
If you're a fan of zucchini, you should definitely check out these amazing recipes:
- Crispy Parmesan Zucchini Fries
- Easy Cheesy Zucchini Bites
- Three Cheese Zucchini Tart
- Creamy Puréed Zucchini Soup
- Zoodles
I first posted this amazing recipe on September 6, 2017. Since then, it's been one of my favorite vegetable casseroles.
This post includes the same delicious recipe with updated text and photos.
I hope you liked this recipe for Easy Make-Ahead Zucchini Gratin as much as I do. If so, please consider rating it and leaving a comment. Also, if you’d like to receive notifications of new posts by email, enter your email address in the Subscribe box.
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Easy Make Ahead Zucchini Gratin
Ingredients
- ½ cup (2 ounces) grated Gruyère cheese (See Tip 1)
- ½ cup (1.5 ounces) Panko breadcrumbs (See Tip 2)
- 2 large zucchini, about 1 pound total
- 1 large onion (between 8 and 9 ounces)
- 1 teaspoon Kosher salt, divided
- 4 Tablespoons butter, divided
- 1 ½ Tablespoons all-purpose flour
- ¾ cup (6-ounces) milk
- ¼ teaspoon freshly ground black pepper
- ⅛ teaspoon freshly ground nutmeg (See Tip 3)
Instructions
- Preheat oven to 400° F. Spray a casserole dish with nonstick spray. Set aside.
- Combine Gruyère and Panko breadcrumbs in a bowl; set aside.
- Scrub zucchini under cold water; cut off the two ends, but do not peel. Cut off two ends of the onion and peel. Grate the zucchini and onion in a food processor or box grater; toss with ½ teaspoon salt in a colander. Let sit for 30 minutes.
- Squeeze liquid from zucchini and onion with your hands. Then, place in a double paper towel and continue squeezing as much liquid as possible. (See Tip 4)
- Heat 3 tablespoons of the butter to foaming over medium heat in a 12-inch nonstick skillet. Add the grated zucchini and onion. Cook for 3 to 5 minutes, just until tender. Season with remaining ½ teaspoon of salt, pepper, and nutmeg. Add flour; stir well to combine and cook for a minute or two.
- Add milk; stir constantly until thickened and bubbly. Correct the seasonings.
- Transfer the zucchini mixture to the prepared casserole dish. Top with Gruyère/Panko mixture. Dot with the remaining tablespoon of butter. Can be made ahead of time up to this point. (See Tip 5)
- Bake in a preheated 400ºF oven for 20 minutes or until bubbling hot and golden browned. Yield: 4 servings. (See Tip 6)
Video
Tips/Notes
- You may substitute Swiss cheese, Cheddar cheese,heese, Monterey Jack c or Fontina cheese for the Gruyère cheese.
- May use plain breadcrumbs in place of the Panko.
- May use store-bought ground nutmeg in place of freshly ground nutmeg.
- You'll be surprised at how much liquid you can squeeze from the zucchini and onion! The reserved liquid from the zucchini and onion can be used in sauces or gravies.
- Cover and refrigerate for up to a day if made ahead of time. Add 5 minutes to the baking time
- Any leftovers can be reheated in a 350°F oven for 10 to 15 minutes. They can also be reheated in the microwave for several minutes. However, if reheated in the microwave, the cheese topping will lose its crispiness.
Jonathan Bryans says
.....it was so delicious that I am making it a second time to take to a potluck Thanksgiving dinner happening tonight. This time I found some Gruyere instead of the cheddar I put on last time. it's such a winner!!
Chula King says
Gruyère is my favorite for this gratin. Happy Thanksgiving!
Jonathan Bryans says
My five stars are in anticipation of the final result. I love the idea of baked Zucchini and onion with a taint of nutmeg. Actually, I also added a grated deep orange sweet potato for kicks. The dish is settled in my fridge to bake for tomorrow morning, when I shall eat some of it for my work lunch with a dressed crisp lettuce salad. I am sure my 5 stars will prove right....and thank you for this idea!!
Chula King says
Jonathan, I hope the final result of the recipe is what you had anticipated!
Chula