Zucchini and yellow Squash Au Gratin
Zucchini and Squash Au Gratin is a creamy, cheesy, and elegant side dish that turns humble summer vegetables into a savory, golden-baked delight. Thinly sliced zucchini and yellow squash are layered with a garlicky cream sauce and a blend of cheeses, then baked until bubbly and crisp on top. It’s perfect for summer dinners, holiday meals, or potlucks.
Total Time
Prep Time: 20 minutes
Cook Time: 30–35 minutes
Resting Time: 5–10 minutes
Total Time: ~55 minutes
Ingredients
2 medium zucchini, thinly sliced (about ¼-inch thick)
2 medium yellow squash, thinly sliced
1 tsp salt (for drawing moisture)
½ tsp ground black pepper
For the Sauce
2 tbsp olive oil
2 garlic cloves, minced
2 tbsp all-purpose flour
1¼ cups whole milk (or half-and-half for richer flavor)
½ cup grated Parmesan cheese
¾ cup shredded Gruyere or sharp white cheddar
Salt and pepper to taste
Optional: pinch of nutmeg for extra depth
Topping
¼ cup breadcrumbs (Panko or fresh)
2 tbsp grated Parmesan
1 tbsp olive oil
Instructions
1. Prep the Veggies
1. Slice zucchini and squash into even ¼-inch rounds.
2. Lay on paper towels, sprinkle with salt, and let sit for 15–20 minutes to draw out moisture.
3. Pat dry with additional paper towels.
2. Make the Cheese Sauce
1. In a saucepan, melt butter over medium heat. Add garlic and sauté 1 minute.
2. Whisk in flour and cook for 1–2 minutes to form a roux (don’t brown).
3. Gradually whisk in milk, stirring constantly, until smooth and thickened (~3–5 minutes).
4. Remove from heat and stir in cheeses until melted. Season with salt, pepper, and optional nutmeg.
3. Assemble the Gratin
1. Preheat oven to 375°F (190°C).
2. oil a medium baking dish (about 8×8 or 9×9 inches).
3. Layer zucchini and squash alternately in the dish.
4. Pour cheese sauce evenly over the vegetables.
5. In a small bowl, mix breadcrumbs, Parmesan, and olive oil. Sprinkle over top.
4. Bake
Bake uncovered for 30–35 minutes, or until bubbly and golden brown.
If needed, broil the top for 1–2 minutes for extra crispness.
Let sit for 5–10 minutes before serving to thicken slightly.
Chef’s Notes
Gruyere is traditional and adds nuttiness, but sharp cheddar is a great affordable substitute.
You can make this dish ahead and reheat, but it’s crispiest fresh.
Try adding thin slices of potato for a heartier version.
Tips
Use a mandoline for quick, even slicing.
Salt the squash to avoid watery gratin.
Use half zucchini and half yellow squash for visual appeal and balance.
Add fresh herbs like thyme or basil for added flavor.
Frequently asked questions FAQs
Q: Can I make it ahead of time?
A: Yes! Assemble up to a day in advance, cover and refrigerate. Bake just before serving.
Q: What’s the best cheese to use?
A: Gruyere and Parmesan are classic, but cheddar, mozzarella, and fontina work well too.
Q: Can I make it gluten-free?
A: Yes—substitute flour with cornstarch or a gluten-free flour blend and use GF breadcrumbs.
Q: Can I add protein?
A: Absolutely—add cooked bacon, sausage, or shredded rotisserie chicken before baking.
Q: How do I prevent it from getting watery?
A: Salt and pat dry the squash before layering, and bake uncovered to allow steam to escape.
Nutritional Information
Calories: ~220 kcal
Protein: 8g
Carbohydrates: 13g
Sugars: 5g
Fat: 15g
Saturated Fat: 8g
Fiber: 2g
Sodium: ~320mg