Zucchini Rice Gratin

This creamy and cheesy recipe for Zucchini Rice Gratin can be made ahead of time and served on its own or as a side dish.

What’s your favourite summer squash recipe? I have so many, but this is the one I make most often.

Why this recipe is so popular

This baked rice dish is full of fresh, simple ingredients. Caramelized onions give it a sweet and fragrant flavour, while fresh thyme and ground nutmeg add a distinctive earthiness. The zucchini rounds on top of the creamy baked rice hold the gratin cheese topping, which comes out of the oven with a crispy top.

I make this recipe every summer for my Italian family reunion. I have to triple the recipe to make sure there’s enough to go around! Our family loves eating zucchini and many of us grow them in our backyard gardens. This is one of my most requested recipes at family potlucks.

How to make Zucchini Rice Gratin

This is a simple recipe that can be assembled ahead of time and baked when needed. Start by gathering and prepping all the ingredients and then follow my steps below for cooking the rice.

Heaps of onions are given a good amount of cooking time in butter and olive oil until tender and caramelized.

Rice, broth, milk, cheese, ground nutmeg, and fresh thyme are added to the caramelized onions and slow simmered to a rich creamy texture.

The cooked rice is transferred to a baking dish and covered with zucchini rounds arranged scallop style. The zucchini are sprinkled with cheese then the dish is baked in a preheated oven.

Tips for recipe success

• Use sweet onions for this recipe if possible, but other types of onions like yellow cooking onions or Spanish onions work well too.
• Cook the onions low and slow as directed. Don’t skimp on the cooking time.
• Make this dish vegetarian by using the vegetable broth option.
• Use fresh thyme (as opposed to dried thyme) since the fragrance and flavour of thyme (sharp grass, wood, and floral notes) is what balances out this dish.
• Slice the zucchini rounds about ¼” thick as you want them to hold up during the baking time and keep a bit of their crunch after they’re baked.
• This recipe can be assembled early in the day or a day ahead, stored in the refrigerator then baked when needed. In this case, bring the dish to room temperature for 1 hour before placing in the preheated oven, and increase the baking time by 10 – 15 minutes.
• Allow about 5 – 10 minutes for the baked rice to set before serving; this makes it much easier to divide the portions.

Serve this cheesy and creamy rice while it’s still hot and enjoy the naturally sweet and fragrant flavour. Let me know what you think about this dish!

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Zucchini Rice Gratin

A gratin rice dish with caramelized onions, nutmeg, and thyme topped with zucchini rounds and crispy shredded cheese.

Servings 8

Ingredients

• 1 tablespoon butter
• 1 tablespoon olive oil
• 4 cups diced sweet onion (about 3 – 4 medium onions)
• 1 ½ cups long grain rice
• 2 cups chicken broth (or vegetable broth for vegetarian version)
• 1 cup milk
• ½ teaspoon ground nutmeg
• 1 teaspoon kosher salt
• ½ teaspoon freshly ground black pepper
• 2 tablespoons chopped fresh thyme, plus more thyme sprigs for garnish
• 1 ½ cups shredded mozzarella, divided ½ cup and 1 cup
• 3 medium zucchini, sliced into ¼” rounds
• 2 tablespoons freshly grated Parmesan cheese

Instructions

1. Preheat oven to 375 degrees F. Prepare a 9 x 13” baking dish by greasing the bottom and sides with oil or cooking spray.

2. In a 4 or 5 qt Dutch oven, melt the butter over medium-high heat then add the olive oil.

3. Add diced onions and sauté for 10 minutes while stirring. Reduce heat to low and cook onions uncovered for another 15 - 20 minutes, stirring occasionally, until the onions are tender, golden and caramelized.

4. Bring the heat back to medium-high. Add rice and toast the rice, while stirring, for about 1 – 2 minutes.

5. Add chicken (or vegetable broth), milk, nutmeg, salt and pepper and stir to combine. Cook until the rice comes to a gentle boil then reduce heat to medium-low. Cover and simmer for 18 - 20 minutes until all the liquid has been absorbed. Remove from heat and stir in thyme and ½ cup of the mozzarella cheese.

6. Transfer rice to the prepared baking dish and spread evenly while packing it down. Top the rice with a thick layer of zucchini slices arranged scallop style, slightly overlapping each other. Sprinkle top with remaining 1 cup mozzarella cheese and Parmesan cheese.

7. Bake for 25 - 30 minutes until bubbly and the top is golden brown. Allow to set for 5 - 10 minutes before serving. Garnish top with more thyme.