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Easy Make Ahead Zucchini Gratin
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4.5 from 14 votes

Easy Make Ahead Zucchini Gratin

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!
Prep Time40 mins
Cook Time20 mins
Total Time1 hr
Course: Side Dish
Cuisine: American
Servings: 4 servings
Calories: 247kcal
Author: Chula King


  • 1/2 cup (2 ounces) grated Gruyère
  • 1/2 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 1/2 Tablespoons all-purpose flour
  • 3/4 cup milk
  • 1/4 teaspoon freshly ground black pepper
  • 1/8 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 1/2 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 1/2 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)


  1. The reserved liquid from the zucchini and onion can be used in sauces or gravies.
  2. Leftovers, if any, can be reheated for several minutes in the microwave, or in a 350°F oven for 10 to 15 minutes.


Calories: 247kcal | Carbohydrates: 16g | Protein: 7g | Fat: 17g | Saturated Fat: 10g | Cholesterol: 47mg | Sodium: 790mg | Potassium: 381mg | Fiber: 1g | Sugar: 6g | Vitamin A: 730IU | Vitamin C: 19.6mg | Calcium: 198mg | Iron: 0.9mg