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 which will have you coming back for more!
When I got home from work, the proverbial question arose – “What’s for dinner?” Given that there’s a major hurricane that could impact us within the week, I thought about making something that could be frozen for hurricane ready meals. The Master Taste Tester suggested instead that we have the leftover Oklahoma Fried Onion Burgers. I thought great and then remembered that I had some zucchini that needed to be used – thus the Easy Make Ahead Zucchini Gratin was born! All through dinner, the Master Taste Tester kept commenting on how good it was – the ultimate compliment!
Another awesome cheese squash casserole is my Cheesy Southern Yellow Squash Casserole. You should try it!
Ingredients for Easy Make Ahead Zucchini Gratin:
I used the following ingredients: Grated Gruyère cheese, Panko breadcrumbs, zucchini, onion, Kosher salt, unsalted butter, freshly ground black pepper, freshly ground nutmeg, all-purpose flour, and milk.
Making the Easy Make Ahead Zucchini Gratin:
I started by combining the Gruyère cheese and Panko breadcrumbs in a small bowl.
Then, I grated the zucchini and onion in my food processor. I transferred the zucchini and onion to a wire mesh strainer set over a bowl and sprinkled on some salt. The idea here was to remove as much of the liquid as possible from both the zucchini and the onion. After 30 minutes, I placed the grated zucchini and onion in a paper towel and squeezed as much liquid as possible from them. 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-high heat until it was foaming. Then, I added the squeezed zucchini and onion and cooked it for about 5 minutes until it was just tender. I stirred in the remaining salt, pepper, and nutmeg. Next, I added the 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 baking dish and topped it with the Gruyère/Panko mixture. Finally, I dotted it with some additional unsalted butter. At this point, I could have refrigerated the gratin for a later use.
Instead, I popped the zucchini into a preheated 400° F oven for about 20 minutes. After 20 minutes, it was bubbling hot and golden brown. Yum!
Easy Make Ahead Zucchini Gratin
- ½ cup (2 ounces) grated Gruyère
- ½ cup (1.5 ounces) Panko breadcrumbs
- 2 large zucchini about 1 pound total
- 1 large onion (about 8 ounces)
- 1 teaspoon Kosher salt divided
- 4 Tablespoons butter divided
- 1 ½ Tablespoons all-purpose flour
- ¾ cup milk
- ¼ teaspoon freshly ground black pepper
- ⅛ teaspoon freshly ground nutmeg
- Preheat oven to 400° F.
- 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 onion, and peel. Grate the zucchini and onion; toss with ½ teaspoon salt in a colander. Let sit for 30 minutes. Then twist by handfuls in the corner of a paper towel or kitchen towel to remove excess liquid—you'll be surprised at the amount of liquid! Save the squeezed out juices. (See Tip 1)
- 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 seasonings.
- Transfer zucchini mixture to a buttered baking and serving dish. Top with Gruyère/Panko mixture. Dot with remaining tablespoon of butter. Can be made ahead of time up to this point.
- Bake in a preheated 400º F oven for 20 minutes or until bubbling hot and golden browned. Yield: 4 servings. (See Tip 2)
Chula's Expert Tips
- The reserved liquid from the zucchini and onion can be used in sauces or gravies.
- Leftovers, if any, can be reheated for several minutes in the microwave, or in a 350°F oven for 10 to 15 minutes.