When summer vegetables are at their peak, there is no better way to showcase them than in a simple but elegant gratin. This dish highlights zucchini and yellow squash, pairing them with a creamy base and a golden cheesy topping. It is comforting yet light, making it perfect as a side dish for both weeknight dinners and special occasions.
Unlike heavier potato-based gratins, this version keeps things fresh by using tender zucchini and yellow squash. The natural sweetness of the squash pairs beautifully with garlic, onion, and Italian seasoning, while the cream and cheeses bring richness. The result is a bubbling dish with layers of tender vegetables coated in cream and topped with a golden crust of mozzarella and Parmesan.
This recipe is simple to prepare, requiring only a handful of ingredients and about 15 minutes of hands-on time. The oven does the rest of the work, transforming basic vegetables into a savory side that feels special without being complicated.
Ingredients
2 medium zucchini
2 medium yellow squash
1 tablespoon olive oil or butter
2 cloves garlic, minced
1/2 cup chopped onion (optional)
1 cup shredded mozzarella cheese
1/2 cup grated Parmesan cheese
1/2 cup heavy cream or whole milk
Salt and pepper to taste
1/2 teaspoon Italian seasoning (optional)
Instructions
Preheat the oven to 375°F (190°C). Lightly grease a baking dish.
Slice zucchini and yellow squash into thin rounds.
Sauté onion and garlic in olive oil or butter over medium heat until softened.
Layer the zucchini and squash in the baking dish. Sprinkle the sautéed garlic and onion over them.
Pour cream or milk evenly over the vegetables.
Sprinkle mozzarella and Parmesan cheeses on top. Season with salt, pepper, and Italian seasoning if using.
Bake uncovered for 25 to 30 minutes, until vegetables are tender and the top is golden and bubbly.
If you want a crispier topping, broil for 2 to 3 minutes at the end.
Let rest for 5 minutes before serving.
Serving Ideas
This dish is versatile enough to be paired with a wide range of main courses. It complements roasted chicken, baked fish, or grilled steak beautifully, adding a creamy vegetable side that balances proteins. For a vegetarian meal, it can be served with crusty bread or alongside a fresh salad. The gratin can also work well on a holiday table as a lighter alternative to heavier casseroles.
Ingredient Notes
Zucchini and yellow squash are interchangeable, but using both creates a more colorful and flavorful dish. Slicing them evenly ensures they cook at the same rate, giving the gratin a uniform texture. The garlic and onion deepen the flavor, but they can be skipped for a simpler version.
Mozzarella provides melt and creaminess, while Parmesan adds sharpness and helps create a golden crust. Using a mix of both cheeses gives the best result, though you can substitute with other cheeses like Gruyère, cheddar, or fontina if you prefer. Heavy cream creates the richest gratin, but whole milk works as a lighter option without sacrificing too much creaminess.
The seasoning can be as simple as salt and pepper, or you can add Italian seasoning, fresh thyme, or basil for an herby note. A pinch of red pepper flakes can also give a subtle kick.
Variations
This gratin is easily customizable. You can add a layer of sliced tomatoes for color and extra sweetness. A sprinkle of breadcrumbs mixed with Parmesan creates a more traditional crusty topping. For added protein, you could mix in cooked bacon bits, pancetta, or shredded rotisserie chicken.
If you prefer a heartier dish, consider adding a layer of thinly sliced potatoes or sweet potatoes with the squash. This creates a layered gratin that is both filling and flavorful. For a Mediterranean twist, you could sprinkle feta cheese on top along with some olives before baking.
Make-Ahead and Storage Tips
The gratin can be assembled ahead of time and refrigerated for up to 24 hours before baking. Simply cover the dish tightly with plastic wrap or foil until ready to bake. If baking straight from the fridge, add 5 to 10 minutes to the cooking time.
Leftovers store well in the refrigerator for up to three days. Reheat in the oven at 350°F (175°C) until warmed through, which helps maintain the crispy topping. The gratin can also be reheated in the microwave, though the topping will be softer. Freezing is possible, but because zucchini and squash release water when thawed, the texture may be softer than when freshly baked.
Why This Recipe Works
Zucchini and yellow squash have a naturally high water content, which can make them tricky in baked dishes. In this gratin, the cream and cheese help absorb and blend with the moisture, preventing the dish from becoming watery. Sautéing the garlic and onion adds flavor without overpowering the delicate squash, while the combination of mozzarella and Parmesan ensures a gooey yet crisp topping.
This dish strikes a balance between rich and fresh. It delivers the comfort of baked cheese and cream but with the lightness of summer vegetables. It is simple enough for a weeknight side dish but elegant enough to bring to a dinner party.
A Versatile Seasonal Dish
One of the best things about this gratin is how it highlights seasonal produce. In the summer, when zucchini and yellow squash are abundant, it’s a perfect way to make use of the harvest. However, it also works well year-round since these vegetables are widely available. The recipe’s flexibility means it can be adapted with whatever ingredients you have on hand, making it a reliable go-to dish.
Conclusion
Zucchini and Yellow Squash Au Gratin is proof that a handful of simple ingredients can be transformed into something greater than the sum of its parts. The creamy texture, bubbling cheese, and tender vegetables create a side dish that feels indulgent yet light. Whether served at a family meal, brought to a potluck, or placed on a holiday table, it is sure to disappear quickly.
With its balance of flavors, ease of preparation, and adaptability, this recipe is one you’ll find yourself turning to again and again.