Zucchini Gratin

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zucchini gratin in cast iron skillet

Who doesn’t love any dish that involves a heck of a lot of cheese melted and crisped to perfection? Dishes prepared “au gratin” are no exception. Although potatoes “au gratin” are commonplace in France, we swap the starchy potatoes for thinly sliced zucchini!

Don’t let the use of green vegetables fool you. There is simply no better way to eat zucchini than “au gratin.” The soft layers of zucchini flavored with caramelized shallots are complimented with drizzles of heavy cream and layers of gruyere cheese and panko.

This zucchini gratin will add excitement to any ordinary everyday main course, whether served alongside a well-seasoned chicken breast or a poached salmon!

sliced zucchini on cutting board


What is Au Gratin or Gratinée?

Au gratin or gratinée is a French cooking method in which vegetables are baked in a shallow dish and topped with a bunch of cheese and possibly breadcrumbs until it melts and forms a crispy crust.

The term gratin is derived from the French verb “gratiner,” which means to scratch or scrape. The act of breaking through that crispy crust of cheese on any dish prepared “au gratin” evokes that feeling of “scratching” or “scraping” through the crust.

gruyere cheese in a dish

What Type of Baking Dish to Use

For dishes “au gratin,” any shallow oven-proof baking dish will work well. Our favorite is the Le Creuset cast-iron oven-proof skillet. For this recipe, we use the 10.25-inch diameter (27 cm) skillet.

Essential Ingredients for Dishes “Au Gratin”

  • Heavy Cream
  • Egg
  • Gruyere Cheese
  • Breadcrumbs
gratinee mixture of heavy cream, egg, and cheese in a bowl

The Importance of Heating the Cream

Our recipe requires you to heat the heavy cream before whisking it with the egg and folding in the cheese. The importance of this step is to ensure the dish cooks more quickly. We use heavy cream for this recipe because it does not easily break or curdle when heated.

Caramelizing the Shallots - Slow and Low

For this dish, you will need to caramelize the shallots before adding the zucchini slices. Caramelization occurs when the shallots are cooked at a very low temperature and the natural sugars in the shallots slowly draw out.

The key to caramelization is “slow and low.” In other words, cook the shallots at a very low temperature in a cast-iron skillet for 20-30 minutes to achieve the desired result. If it takes longer to cook, do not increase the temperature; just wait. Keep the temperature of the stovetop at medium-low heat. 

Time is the key to achieve ideal caramelization. If you increase the heat, the moisture in the shallots may draw out too quickly, causing them to burn before they develop that sweet onion jam flavor. Patience is key.

caramelized shallots in cast iron pan

Evenly Distribute the Sauce and Cheese

Distribute the zucchini slices evenly in the baking dish. Once the heavy cream, egg, and cheese are whisked together, pour the mixture evenly over the zucchini slices. Then, top it evenly with cheese and panko breadcrumbs. We recommend using a box grater for a large grate of the Gruyere cheese. If you don’t have enough cheese to fully cover the zucchini slices, add more grated cheese to guarantee that bubbly “gratin” quality.

zucchini gratin in cast iron before cooking

What Does It Look Like When Baked?

Bake the zucchini gratin until the cheese melts and crisps up, forming a golden-brown crust over the entire dish. When you see that golden-brown crust, the dish is done, and it is ready to serve!

zucchini gratin in cast iron skillet

How Long Does Zucchini Gratin Take to Bake

For 1.25 cups of cheese, the cooking time is approximately 25 to 30 minutes at 375 degrees Fahrenheit (191 degrees Celsius). However, if you opt for more cheese, such as 2 cups of cheese, the cooking time is approximately 30 to 40 minutes.

What to Serve It With

zucchini gratin in cast iron skillet

Reheating and Storage

Store it in the refrigerator in an airtight container and consume it for up to two days. You can reheat it in the microwave for one minute at 70%. However, the best way to reheat this dish is to bake it in the oven at 325 degrees Fahrenheit (163 degrees Fahrenheit) in an ovenproof dish for 10-20 minutes or until warm throughout. 10 minutes for one to two portions and 20 minutes for a larger quantity.

Wine Pairing

Visit your local liquor store and request a bottle featuring these characteristics to find the perfect pair.

  • Color: white
  • Notes: pear, thyme, lemon, almond, and ripe gooseberry
  • Geography: old world
  • Structure: full-bodied, mild acidity, aged in oak
zucchini gratin on fork

Purge Your Fridge

You just finished scarfing down our zucchini gratin, and you are left with some extra heavy cream and flat-leaf parsley. Here are some tasty options for ridding your fridge of the excess ingredients:

zucchini gratin in cast iron skillet
Zucchini Gratin
Nothing satisfies quite like our ooey-gooey cheesy zucchini gratin that pairs wonderfully with any French favorite main course!
Prep Time 10 minutes
Cook Time 1 hour 10 minutes
Total Time 1 hour 20 minutes
Course Dinner, Side Dish
Cuisine French
Servings 6
Calories 236 kcal


  • 2 zucchinis medium-sized
  • 2 shallots thinly sliced lengthwise
  • 1 tsp olive oil
  • 1 tbsp unsalted butter
  • 1 egg
  • 1/2 cup heavy cream
  • 1 cup Gruyere cheese grated
  • 1/4 cup Parmesan cheese grated
  • 1/4 cup panko breadcrumbs
  • 2 tbsp flat-leaf parsley finely chopped
  • 1 1/8 tsp salt 1 tsp to season heavy cream, egg, and cheese mixture and 1/8 tsp to season the shallots
  • ground pepper


1. Preheat the Oven and Prepare Vegetables and Cheese
  • Preheat the oven to 375 degrees Fahrenheit (191 degrees Celsius).
  • Thinly slice zucchini and them between layers of paper towel to press out the excess liquid.
  • Thinly slice shallots (lengthwise) and finely chop flat-leaf parsley. Set aside.
  • Grate Gruyere and Parmesan cheese using a box grater for a large grate. Set aside.
2. Whisk Together Eggs and Heavy Cream and Fold in Cheese
  • Warm the heavy cream in a saucepan on the stovetop at medium heat.
  • Whisk egg and warm heavy cream together in a mixing bowl.
  • Fold in 3/4 of the grated cheese.
  • Season with salt and pepper.
3. Sauté the Shallots until Caramelized
  • Place a cast-iron skillet on the stovetop at medium-low heat.
  • Add butter and olive oil. Allow the butter to melt and bubble.
  • Add shallots, and season with salt and pepper.
  • Sauté them for 20-30 minutes or until caramelized.
4. Sauté the Zucchini for 10 minutes
  • Turn the stovetop up to medium heat.
  • Add zucchini slices.
  • Sauté them for 10 minutes.
  • Turn the stovetop off.
5. Pour in Egg, Heavy Cream, and Cheese Mix
  • Pour the egg, warmed heavy cream, and cheese mixture over the zucchini slices in the cast-iron skillet.
  • Sprinkle excess cheese, panko breadcrumbs, and flat-leaf parsley on top.
  • Season with additional ground pepper.
6. Bake and Serve
  • Bake in the oven for 25-30 minutes.
  • Serve and enjoy.



Calories: 236kcalCarbohydrates: 6gProtein: 11gFat: 19gSaturated Fat: 11gTrans Fat: 1gCholesterol: 87mgSodium: 620mgPotassium: 258mgFiber: 1gSugar: 3gVitamin A: 874IUVitamin C: 14mgCalcium: 310mgIron: 1mg
Keyword approachable, authentic, Easy, one-pan, vegetarian
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About Savory Suitcase
Hello, I’m Kristina, Founder and Head Blogger of Savory Suitcase… the one-stop-shop for the international foodie. 

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Hello, I’m Kristina, Founder and Head Blogger of Savory Suitcase… the one-stop-shop for the international foodie.


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