Creamiest, cheesiest zucchini gratin bakes zucchini coins in a velvety cream-and-Parmesan sauce under a golden cap of sharp white cheddar. Sautéing the zucchini first keeps the gratin from turning watery. It feeds eight and tastes like a restaurant side dish.
Craving the rich, decadent comfort of gourmet mac and cheese but want to keep things on the lighter side? Meet your new favorite side dish: the Creamiest, Cheesiest Zucchini Gratin. This recipe transforms humble zucchini into a bubbling, golden-brown masterpiece. Tender zucchini coins are bathed in a velvety cream and Parmesan sauce, layered with sharp white cheddar, and baked to perfection. It’s an incredible way to use up summer squash and is so versatile it can stand next to a roasted chicken or be the star of the show itself. Get ready for a restaurant-quality gratin that’s shockingly easy to make at home.
Ingredients
• 2 tablespoons butter or ghee / 28 g (0.99 oz)
• 1 small onion, halved and thinly sliced / 110 g (3.9 oz)
• 3 cloves garlic, minced
• 4 medium zucchini, about 8 inches, sliced into coins / 800 g (28.2 oz)
• 1 teaspoon sea salt / 6 g (0.21 oz)
• ½ teaspoon ground black pepper / 1 g (0.04 oz)
• ¼ teaspoon ground nutmeg / 0.5 g (0.02 oz)
• For the Sauce
• 1 cup heavy cream / 240 ml
• ½ cup grated Parmesan cheese / 50 g (1.76 oz)
• 2 tablespoons butter / 28 g (0.99 oz)
• 1½ cups shredded sharp white cheddar cheese, divided / 170 g (6 oz)
Instructions
1. Directions
2. Preheat your oven to 425°F / 220°C. Lightly grease a 10-inch casserole or baking dish.
3. In a large skillet, melt 2 tablespoons (30 ml / 1 fl oz) of butter over medium heat. Add the sliced onion and cook until it begins to soften and turn translucent, about 5 minutes. Stir in the minced garlic and cook for one more minute until fragrant.
4. Add the zucchini coins, sea salt, black pepper, and nutmeg to the skillet. Continue to cook, stirring occasionally, for about 5-7 minutes, until the zucchini is crisp-tender.
5. While the zucchini cooks, prepare the sauce. In a microwave-safe bowl, combine the heavy cream, grated Parmesan cheese, and the remaining 2 tablespoons (30 ml / 1 fl oz) of butter. Microwave in 30-second intervals, stirring in between, until the cream is warm and the butter is fully melted. Alternatively, you can warm these in a small saucepan over medium-low heat on the stovetop.
6. Assemble the gratin. Spread half of the cooked zucchini mixture in an even layer in your prepared casserole dish. Sprinkle with ¾ cup of the shredded cheddar cheese. Top with the remaining zucchini mixture.
7. Pour the warm cream sauce evenly over the top of the zucchini. Sprinkle the remaining ¾ cup of cheddar cheese over the entire dish.
8. Bake for 20 minutes, or until the sauce is bubbling and the cheese on top is melted and golden brown. Let the gratin rest for 5-10 minutes before serving to allow it to set.
Nutritional Information
• Nutrition Information
• Serves: 8 | Calories: 285 | Fat: 25 g (0.88 oz) | Protein: 9 g (0.32 oz) | Total Carbs: 5.3 g (0.19 oz) | Dietary Fiber: 1.3 g (0.05 oz) | Net Carbs: 4 g (0.14 oz)
Pro Tips
• To avoid a watery gratin, sauté the zucchini until it’s just crisp-tender. It will finish cooking in the oven, and this initial step helps release some of its moisture.
• Experiment with cheeses! Swap the cheddar for Gruyère for a nutty, classic flavor, or use a mix of pepper jack and mozzarella for a spicy kick with a satisfying cheese pull.
• This dish can be assembled up to 24 hours in advance. Cover the unbaked gratin tightly and refrigerate. When ready to eat, bake from cold, adding 5-10 minutes to the total cook time.
FAQ
Q: How do I prevent my zucchini gratin from being watery
A: To avoid a watery gratin, it’s important to sauté the zucchini until it is crisp-tender before assembling the dish. This initial cooking step helps release some of the zucchini’s natural moisture, ensuring a creamy final texture.
Q: Can I make this zucchini gratin ahead of time
A: Absolutely. You can assemble the entire gratin up to 24 hours in advance. Cover the unbaked dish tightly and store it in the refrigerator. When you’re ready to cook, simply add 5-10 minutes to the total bake time.
Q: What other cheeses can I use in this gratin
A: This recipe is very flexible. For a classic, nutty flavor, try substituting the cheddar with Gruyère. For a spicy kick with a satisfying cheese pull, a mix of pepper jack and mozzarella is an excellent choice.
Q: Is this zucchini gratin recipe low carb
A: Yes, with only 4 grams (0.14 oz) of net carbs per serving, this creamy zucchini gratin is a great low-carb and keto-friendly side dish.
Pro Tips
- Sauté the zucchini until just crisp-tender before assembling — this releases moisture so the gratin bakes creamy instead of soupy.
- Warm the heavy cream, Parmesan, and butter together before pouring; the sauce blends into the layers far more evenly.
- Swap the cheddar for Gruyère for a nutty finish, or use pepper jack and mozzarella for a spicy cheese pull.
- Assemble up to 24 hours ahead, cover tightly, and refrigerate — bake from cold with 5-10 extra minutes in the oven.
- Let the gratin rest 5-10 minutes after baking so the sauce sets around the zucchini.
Frequently Asked Questions
Is zucchini gratin keto?
Yes: each serving has 5.3 g of total carbs and 1.3 g of fiber (4 g net), with 25 g of fat and 9 g of protein.
How do I keep the gratin from getting watery?
Sauté the zucchini to crisp-tender first to drive off moisture, and let the baked gratin rest 5-10 minutes before serving.
Can I assemble it ahead of time?
Up to 24 hours: cover the unbaked gratin tightly, refrigerate, and bake from cold with an extra 5-10 minutes of cook time.
Can I change the cheeses?
Yes — Gruyère gives a nutty, classic flavor, while pepper jack and mozzarella bring spice and a satisfying cheese pull.
Recipe card below.
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Creamiest, Cheesiest Zucchini Gratin
Ingredients
Method
- Directions
- Preheat your oven to 425°F / 220°C. Lightly grease a 10-inch casserole or baking dish.
- In a large skillet, melt 2 tablespoons (30 ml / 1 fl oz) of butter over medium heat.
- Add the sliced onion and cook until it begins to soften and turn translucent, about 5 minutes.
- Stir in the minced garlic and cook for one more minute until fragrant.
- Add the zucchini coins, sea salt, black pepper, and nutmeg to the skillet.
- Continue to cook, stirring occasionally, for about 5-7 minutes, until the zucchini is crisp-tender.
- While the zucchini cooks, prepare the sauce.
- In a microwave-safe bowl, combine the heavy cream, grated Parmesan cheese, and the remaining 2 tablespoons (30 ml / 1 fl oz) of butter. Microwave in 30-second intervals, stirring in between, until the cream is warm and the butter is fully melted. Alternatively, you can warm these in a small saucepan over medium-low heat on the stovetop.
- Assemble the gratin.
- Spread half of the cooked zucchini mixture in an even layer in your prepared casserole dish.
- Sprinkle with ¾ cup of the shredded cheddar cheese.
- Top with the remaining zucchini mixture.
- Pour the warm cream sauce evenly over the top of the zucchini.
- Sprinkle the remaining ¾ cup of cheddar cheese over the entire dish.
- Bake for 20 minutes, or until the sauce is bubbling and the cheese on top is melted and golden brown.
- Let the gratin rest for 5-10 minutes before serving to allow it to set.
