Zucchini gratin with yellow squash is a simple yet elegant dish that transforms fresh summer vegetables into a warm, creamy, and satisfying casserole. Perfect as a side dish or a vegetarian main course, this recipe combines thinly sliced zucchini and yellow squash, layered with rich cheese and sometimes a light cream sauce, then baked until golden and bubbling.

This dish is especially popular in warmer months when zucchini and squash are in season, but it can be enjoyed year-round. It’s a fantastic way to use up garden vegetables or highlight seasonal produce from your local market. Zucchini gratin is both comforting and light, with a tender texture and subtle flavor that pairs well with a wide variety of meals. Whether you’re cooking for a family dinner, a potluck, or a holiday gathering, this gratin is a crowd-pleaser that brings rustic charm and healthy ingredients to the table.

Ingredients Overview

The beauty of zucchini gratin with yellow squash lies in its simplicity. The basic ingredients are easy to find and can be adapted to suit your dietary needs or flavor preferences.

Main ingredients include:

Zucchini and yellow squash, thinly sliced
Cheese (commonly Gruyère, Parmesan, or mozzarella)

Heavy cream or milk
Garlic, salt, pepper
Olive oil or butter

Optional additions:

Thinly sliced onions or shallots

Fresh herbs like thyme, basil, or parsley
Breadcrumbs or crushed crackers for topping

You can also modify the cheese to fit your taste or what’s in your fridge. Gruyère gives a nutty, robust flavor, while mozzarella adds creaminess. Parmesan is ideal for a sharp finish on top. For a lighter dish, you can use milk instead of cream, or even Greek yogurt mixed with broth.

Zucchini vs. Yellow Squash:
Zucchini is slightly firmer and darker green, while yellow squash is a bit sweeter and softer. Using both adds color, texture, and balance to the gratin.

This recipe is naturally vegetarian, and with a few swaps, it can be made gluten-free, low-carb, or keto-friendly.

Step-by-Step Instructions for Making Zucchini Gratin

Making zucchini gratin with yellow squash is straightforward, but a few careful steps will ensure it turns out perfectly.

Step 1: Prep the vegetables
Wash and thinly slice both zucchini and yellow squash, about 1/8-inch thick. Uniform slices cook evenly. Sprinkle with salt and let them sit for 20–30 minutes in a colander to draw out moisture. Pat dry with paper towels. This step helps prevent a watery gratin.

Step 2: Prepare the cheese mixture or sauce
In a saucepan over medium heat, melt 2 tablespoons of butter. Add minced garlic and cook for 1 minute. Stir in 1 cup of cream or milk, and slowly add 1½ cups of grated cheese (such as Gruyère and Parmesan). Stir until melted and smooth. Season with salt, pepper, and a pinch of nutmeg or thyme if desired.

Step 3: Assemble the gratin
Preheat oven to 375°F (190°C). Lightly grease a baking dish with oil or butter. Layer zucchini and yellow squash slices in overlapping rows or circles. Pour the cheese sauce evenly over the top. Add a final sprinkle of cheese and optionally a layer of breadcrumbs.

Step 4: Bake
Cover with foil and bake for 25–30 minutes. Uncover and bake an additional 10–15 minutes, or until the top is golden and bubbling.

Step 5: Finish and serve
Let the gratin rest for 5–10 minutes before serving. This allows it to set slightly and makes it easier to slice.

Tip: Broil for the last 2–3 minutes if you want a crispy top.

Recipe Variations

Zucchini gratin with yellow squash is versatile and easy to customize. Here are some delicious variations to suit different diets and preferences:

1. Low-Carb or Keto-Friendly Version:
Replace breadcrumbs with crushed pork rinds or omit entirely. Use heavy cream and full-fat cheeses to increase fat content without adding carbs.

2. Vegan or Dairy-Free Option:
Use plant-based milk (like oat or almond) and dairy-free cheeses. A cashew cream base seasoned with nutritional yeast can also substitute for a traditional cheese sauce.

3. Mediterranean Style:
Add kalamata olives, sun-dried tomatoes, and crumbled feta cheese for a Mediterranean twist. Finish with a drizzle of olive oil and fresh oregano.

4. Protein-Boosted Gratin:
Mix in cooked shredded chicken, ground turkey, or cannellini beans between the squash layers. This turns the side dish into a full meal.

5. Rustic Herb and Onion Gratin:
Sauté onions with garlic and layer them between the squash slices. Add fresh rosemary or thyme to the cheese sauce for deeper flavor.

6. Cheesy Cracker Topping:
Crushed Ritz crackers or seasoned breadcrumbs combined with melted butter and Parmesan can be added on top before baking for a crunchy crust.

7. Tomato-Layered Gratin:
Add thin tomato slices in between the squash for a slightly acidic contrast to the creamy cheese.

Experimenting with different cheeses, spices, or vegetable combinations allows you to make this dish your own while maintaining its comforting foundation.

Pairing and Serving Suggestions

Zucchini and yellow squash gratin makes an excellent side dish for a variety of main courses. Its creamy, cheesy texture complements grilled meats such as steak, chicken, or pork chops. It also pairs well with roasted or baked fish like salmon or cod.

For a vegetarian meal, serve the gratin alongside a hearty salad, such as a quinoa and chickpea salad or a warm lentil dish. It also works beautifully with a bowl of tomato soup or crusty bread for a light lunch.

During the holidays or at family gatherings, zucchini gratin is a fantastic addition to the dinner table. Its vibrant color and appealing aroma make it stand out among other casseroles.

Garnish the dish with a sprinkle of fresh parsley or basil before serving for added freshness and color. Serve directly from the baking dish to keep the layers intact and retain heat.

Storage, Leftovers, and Reheating Tips

Zucchini gratin with yellow squash stores well and makes great leftovers. Once cooled, transfer the gratin into an airtight container or cover the baking dish tightly with plastic wrap or aluminum foil. Store it in the refrigerator for up to 3–4 days.

To reheat, use an oven or toaster oven for the best texture. Preheat to 350°F (175°C) and warm the gratin for about 15–20 minutes, or until heated through. This method helps restore the crispness of the top layer. If you’re short on time, reheating in the microwave for 1–2 minutes per portion works, though it may soften the texture.

Freezing is possible but not ideal due to the high water content in squash, which can make the gratin watery when thawed. If you do freeze it, wrap portions tightly and use within one month. Thaw in the fridge overnight and reheat in the oven for better results.

Health Benefits of Zucchini and Yellow Squash

Both zucchini and yellow squash are nutrient-dense, low-calorie vegetables packed with health benefits. They are excellent sources of vitamin C, vitamin A, and potassium, supporting immune function, vision, and heart health. Their high water and fiber content also aid digestion and help maintain hydration.

Zucchini, in particular, is rich in antioxidants such as lutein and zeaxanthin, which promote eye health. Yellow squash contains manganese, a mineral important for bone development and metabolism. Because they are low in carbs and calories, both vegetables are ideal for weight-conscious or low-carb diets.

The fiber in these squashes helps regulate blood sugar levels and promotes a feeling of fullness, making them an excellent choice for balanced eating. When paired with healthy fats and protein, like in a gratin, zucchini and yellow squash contribute to a satisfying, nutritious meal that supports long-term wellness.

Zucchini Gratin vs. Other Squash Casseroles

Zucchini gratin stands apart from other squash casseroles due to its refined texture and minimal ingredient list. Unlike traditional squash casseroles that often use eggs, crushed crackers, or canned soups, zucchini gratin typically features a lighter base of cheese and cream, allowing the vegetables to shine.

Scalloped squash casseroles tend to have a denser, more eggy consistency, often resembling a savory custard. Ratatouille, another squash-based dish, incorporates tomatoes, eggplant, and herbs in a more rustic, stew-like form, usually without cheese.

Potato gratins are richer and more filling due to the starchy nature of potatoes, while zucchini gratin remains lighter and more vegetable-forward. It offers a more elegant presentation and a balance between creamy richness and freshness.

For those seeking a healthier or gluten-free option, zucchini gratin is a great alternative to heavier casseroles. It highlights seasonal produce without overwhelming it with processed ingredients or heavy starches.

FAQs Section – People Also Ask

Can I make zucchini gratin ahead of time?
Yes, you can assemble the gratin a day in advance and store it covered in the refrigerator. Wait to bake it until you’re ready to serve. Let it sit at room temperature for 20–30 minutes before baking to ensure even cooking.

How do you keep zucchini gratin from getting watery?
The key is to salt the sliced squash beforehand and let it drain. This draws out excess moisture. Also, avoid using overly watery ingredients and don’t overbake the dish, which can break down the vegetables too much.

What cheese works best for gratin?
Gruyère, Parmesan, and mozzarella are popular choices. Gruyère provides a nutty depth, Parmesan offers sharpness, and mozzarella adds creaminess. A blend often yields the best flavor and texture.

Can I use only yellow squash or only zucchini?
Absolutely. The recipe works well with just one type of squash. Using both provides visual contrast and flavor balance, but it’s flexible based on what you have on hand.

Is zucchini gratin keto-friendly?
Yes, especially if you avoid breadcrumbs and use heavy cream and full-fat cheese. It’s low in carbs and high in fat, making it suitable for a ketogenic diet.

Can I freeze zucchini gratin?
Freezing is possible but not ideal. The texture may become mushy due to the water content in the squash. If freezing, use airtight containers and reheat in the oven for better results.

What herbs go best in a squash gratin?
Thyme, basil, oregano, and parsley pair well with the mild flavor of squash. Fresh herbs enhance the aroma and add depth.

Can I make this dish without cream or cheese?
Yes. Use a béchamel sauce made with plant-based milk and flour for a dairy-free version, or keep it simple with olive oil and herbs for a lighter dish.

Final Thoughts and Recipe Recap

Zucchini gratin with yellow squash is a versatile, flavorful dish that celebrates the freshness of seasonal vegetables in a comforting, creamy format. With minimal ingredients and endless variations, it’s suitable for weeknight dinners, special occasions, or holiday spreads.

To make it, simply slice and salt the squash, prepare a quick cheese sauce, layer everything in a baking dish, and bake until golden. Whether you stick to the classic version or experiment with your own additions, this gratin is sure to become a favorite. Try it once, and you’ll return to it all season long.

Zucchini Gratin with Yellow Squash

Author: Hamza

Print Recipe

Description

This Zucchini Gratin with Yellow Squash is a creamy, cheesy vegetable casserole that makes the perfect side dish or light vegetarian main. Layered with fresh zucchini and yellow squash, a rich cheese sauce, and optional crisp topping, this recipe is both comforting and elegant. Ideal for using up summer produce or serving during the holidays, it’s easy to customize with herbs, alternative cheeses, or added protein. With minimal prep and wholesome ingredients, it’s a crowd-pleaser for any occasion.

Ingredients

Scale

2 tablespoons butter
1/2 onion thinly sliced
1 small zucchini sliced in rounds 1/8 to 1/4 inch thick please see notes

1 small yellow squash sliced in rounds 1/8 to 1/4 inch thick please see notes
2 large cloves garlic minced
1/2 cup heavy cream

1/4 cup grated parmesan
1 cup shredded smoked gouda

Instructions

Preheat oven to 450 degrees.

Melt butter in an oven-proof skillet over medium heat. Add onion and cook until the edges start to brown, approximately 5 minutes. Add garlic and cook for an additional 1 minute. Add cream and simmer until bubbly and starting to thicken. Slowly stir in parmesan. Add zucchini and yellow squash and cook an additional 4-5 minutes.
Sprinkle with smoked gouda and bake in the oven for 15-20 minutes or until cheese is golden brown.

Notes

Make Ahead: You can assemble the gratin up to 24 hours in advance and refrigerate. Bake just before serving for best texture.
Watery Gratin Fix: To avoid excess moisture, salt the sliced squash and let it sit for 20–30 minutes, then pat dry thoroughly.

Cheese Options: Gruyère, Parmesan, mozzarella, or a combination all work well. For a sharper flavor, try aged cheddar or fontina.
Dairy-Free/Vegan Adaptation: Use plant-based milk and cheese or a cashew cream sauce for a vegan version.
Low-Carb/Keto Tip: Skip the breadcrumbs and use heavy cream with full-fat cheese to keep it keto-friendly.

Add-Ins: Try sautéed onions, chopped herbs, cooked chicken, or crumbled feta for added variety.
Freezing Note: This dish can be frozen but may become slightly watery upon reheating. Bake from frozen or thaw overnight in the fridge and reheat in the oven.