When summer squash is in season, there’s no better way to enjoy it than in a Zucchini and Yellow Squash Au Gratin. This cheesy, creamy baked dish transforms humble squash into a golden, bubbling, flavor-packed casserole that’s perfect for dinner parties, potlucks, or weeknight meals.
With layers of thinly sliced zucchini and yellow squash, a luscious cream sauce, and a crispy parmesan-panko topping, this gratin is irresistible. Whether you’re serving it as a side or meatless main, it’s a cozy and impressive dish that makes veggies the star.
Ingredients:
- 2 medium zucchinis, thinly sliced
- 2 medium yellow squash, thinly sliced
- 2 tablespoons butter
- 2 cloves garlic, minced
- 1 tablespoon all-purpose flour
- ¾ cup milk
- ½ cup heavy cream
- 1 cup shredded Gruyère or sharp cheddar cheese
- ½ cup grated parmesan cheese (divided)
- ½ teaspoon salt
- ¼ teaspoon black pepper
- ½ teaspoon dried thyme or Italian seasoning
- ½ cup panko breadcrumbs
- 1 tablespoon olive oil or melted butter (for topping)
- Optional: fresh herbs (parsley or chives) for garnish
Preparation:
Step 1: Preheat Oven and Prep Squash
- Preheat oven to 375°F (190°C).
- Thinly slice the zucchini and yellow squash into even ⅛–¼-inch rounds. Pat them dry with paper towels to remove excess moisture.
Step 2: Make the Cream Sauce
- In a medium saucepan, melt butter over medium heat. Add garlic and sauté for 1 minute until fragrant. Whisk in the flour and cook for 1 minute to form a roux.
- Slowly pour in the milk and cream, whisking continuously until the sauce begins to thicken (about 3–4 minutes). Stir in salt, pepper, thyme, and ½ cup of the shredded cheese. Stir until melted and smooth. Remove from heat.
Step 3: Layer the Gratin
- In a greased 9×9-inch or similar baking dish, layer half the sliced squash in an even layer. Pour half of the cream sauce over it. Repeat with the remaining squash and top with the rest of the sauce.
- Sprinkle with remaining ½ cup shredded cheese and ¼ cup parmesan.
Step 4: Add Crunchy Topping
- In a small bowl, mix panko breadcrumbs, the remaining ¼ cup parmesan, and olive oil or melted butter. Sprinkle over the top of the gratin evenly.
Step 5: Bake
- Cover loosely with foil and bake for 25 minutes. Remove foil and bake another 15–20 minutes, until bubbly and golden brown on top.
Step 6: Rest and Serve
- Let the gratin rest for 5–10 minutes before serving to allow it to set. Garnish with fresh herbs, if desired.
Variation:
- Add protein: Mix in cooked bacon, sausage, or shredded chicken for a heartier dish.
- Make it spicy: Add red pepper flakes or diced jalapeños to the sauce.
- Low-carb option: Skip the flour and thicken with a bit of cream cheese.
- Different cheese: Swap Gruyère for sharp white cheddar, fontina, or gouda.
COOKING Note:
To avoid a watery gratin, make sure to pat the squash slices dry and do not overcook the sauce. You can even salt the squash ahead of time, let it sit for 10 minutes, and then blot dry to release extra moisture.
Serving Suggestions:
- With roasted meats: Perfect alongside baked chicken, pork tenderloin, or steak.
- With fresh salad: A crisp green salad balances out the richness.
- As a main dish: Serve with crusty bread for a vegetarian dinner.
- Holiday favorite: A beautiful side for Thanksgiving or Easter meals.
Tips:
- Use a mandoline slicer for even, thin slices.
- Choose squash that’s firm and not overly large for best texture.
- You can prep and assemble ahead of time—just bake right before serving.
- Cover the top loosely with foil during the first bake to prevent over-browning.
⏱️ Time Overview:
- Prep Time: 20 minutes
- Cooking Time: 40–45 minutes
- Total Time: ~1 hour
🍽️ Nutritional Information (per serving, approx. 6 servings):
- Calories: ~260
- Protein: ~10g
- Carbohydrates: ~14g
- Fat: ~19g
- Fiber: ~2g
- Sugar: ~4g
- Sodium: ~330mg
Nutrition varies depending on cheese and topping choices.
❓FAQs
Can I make this ahead of time?
- Yes! You can assemble the dish, cover, and refrigerate for up to 24 hours. Bake just before serving.
Can I freeze it?
- It’s best fresh. The squash can become watery when thawed. If freezing, reheat uncovered in the oven to restore texture.
What’s the best cheese for gratin?
- Gruyère is traditional, but sharp cheddar, fontina, or even mozzarella all work well.
Can I add breadcrumbs on top?
- Yes, panko mixed with parmesan creates a crispy, golden topping.
How do I keep the gratin from being soggy?
- Salt and pat squash dry before layering. Also, don’t overfill the sauce and bake uncovered for a crispy top.
Conclusion:
Zucchini and Yellow Squash Au Gratin is a creamy, crowd-pleasing side dish that turns fresh garden veggies into something decadent and flavorful. The cheesy sauce, crispy topping, and tender squash make this dish ideal for everything from Sunday dinners to holiday feasts.
Easy to make, easy to love—this recipe will become a staple at your table.