Creamy Squash Gratin with Mornay Sauce: A Comforting Classic

Squash Gratin with Mornay Sauce is a decadent baked dish that combines tender slices of squash with a velvety, cheesy béchamel sauce. Topped with a golden crust, this gratin is the epitome of comfort food. Whether you’re preparing it for a holiday feast or a cozy family dinner, this recipe promises to impress with its rich flavors and elegant presentation.

---

Why This Recipe Stands Out

This squash gratin isn’t just another side dish; it’s a celebration of creamy textures and savory flavors. Here’s why you’ll love making it:

• Rich and Creamy Sauce: The Mornay sauce adds indulgent depth with its blend of cheeses.
• Perfectly Tender Squash: Thinly sliced squash bakes to perfection, creating layers of soft, flavorful goodness.
• Versatile and Customizable: From adding herbs to swapping cheeses, this dish can be tailored to suit your taste.
• Make-Ahead Friendly: Prepare it ahead of time and bake when ready—a lifesaver for busy days.
• Seasonal Delight: It’s an excellent way to enjoy fresh squash during peak season.

---

Ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

To make this delicious gratin, you’ll need simple pantry staples and fresh produce. Here’s what goes into the dish:

• Yellow squash or zucchini (thinly sliced)
• Butter (for the roux and greasing the baking dish)
• All-purpose flour (or gluten-free flour for dietary needs)
• Whole milk (unsweetened plant-based milk works too!)
• Gruyère or Swiss cheese (grated for a classic flavor)
• Parmesan cheese (grated for added depth)
• Salt and black pepper (to taste)
• Nutmeg (optional but highly recommended for warmth)
• Garlic (minced, optional for extra flavor)
• Breadcrumbs or additional cheese for topping (optional but encouraged for texture)
• Fresh herbs like thyme or parsley (optional garnish)

---

Step-by-Step Instructions

Preparing the Dish

1. Preheat Your Oven
   Set your oven to 375°F (190°C). Grease a medium-sized baking dish with butter or nonstick spray.
2. Prepare the Squash
   Wash and thinly slice the squash or zucchini. For even slicing, use a mandoline slicer if available. If you prefer firmer squash, steam or sauté the slices briefly until they’re just tender—about 5–7 minutes. Drain any excess liquid to prevent a watery gratin.
3. Make the Roux
   In a saucepan over medium heat, melt the butter. Add the flour and whisk continuously for 1–2 minutes to create a smooth roux. Be careful not to let it brown unless you want a nuttier flavor.
4. Create the Sauce Base
   Gradually pour in the milk while whisking constantly to avoid lumps. Continue cooking until the mixture thickens, which should take about 5 minutes.
5. Add Cheese for the Mornay Sauce
   Remove the pan from heat and stir in the grated Gruyère and half of the Parmesan cheese. Mix until fully melted and smooth. Season the sauce with salt, black pepper, and a pinch of nutmeg. For an aromatic touch, add minced garlic at this stage.
6. Assemble the Gratin
   Arrange the squash slices in the prepared baking dish, overlapping them slightly for a beautiful presentation. Pour the Mornay sauce evenly over the squash, tapping the dish gently to help it settle. Sprinkle the remaining Parmesan and breadcrumbs (if using) on top for a crispy finish.
7. Bake Until Golden
   Place the dish in the preheated oven and bake uncovered for 20–25 minutes, or until the top is golden brown and bubbly. Let the gratin rest for 5 minutes before serving to allow the flavors to meld.
8. Garnish and Serve
   For an extra pop of freshness, sprinkle chopped herbs like thyme or parsley on top before serving.

Save

---

Serving Suggestions and Storage Tips

How to Serve

This squash gratin pairs beautifully with roasted meats, grilled vegetables, or a crisp green salad. Its creamy texture and cheesy richness also make it a satisfying standalone vegetarian main course. Consider pairing it with crusty bread or garlic knots to soak up every last bit of sauce.

Storing Leftovers

Store any leftovers in an airtight container in the refrigerator for up to 3 days. Reheat in a 350°F oven until warm and bubbly, which usually takes about 15–20 minutes. For individual portions, microwaving works but may soften the crunchy topping.

Freezing Recommendation

While freezing isn’t ideal due to the dairy content and squash texture, you can freeze unbaked gratins. Assemble the dish, cover tightly, and freeze for up to one month. When ready to bake, thaw overnight in the fridge and follow the baking instructions.

---

Variations to Try

The beauty of this recipe lies in its versatility. Here are some ideas to switch things up:

• Mixed Vegetables: Add thinly sliced potatoes, carrots, or eggplant for a heartier gratin.
• Cheese Options: Swap Gruyère for white cheddar, Fontina, or smoked mozzarella for unique flavors.
• Low-Carb Version: Use almond flour instead of all-purpose flour and heavy cream instead of milk.
• Herbaceous Twist: Stir fresh basil, chives, or dill into the Mornay sauce for a fragrant twist.
• Spicy Kick: Add a pinch of cayenne or red pepper flakes for a subtle heat.

---

Frequently Asked Questions

What is Mornay sauce?
Mornay sauce is a French béchamel enriched with cheese, typically Gruyère and Parmesan. It forms the creamy base of this gratin.

Can I use zucchini instead of yellow squash?
Absolutely! Zucchini works wonderfully and can be used alone or combined with yellow squash for variety.

Do I need to precook the squash?
Not necessarily. Thinly slicing the squash allows it to cook through in the oven. However, lightly steaming or sautéing it beforehand ensures softer results.

Can I prepare this dish ahead of time?
Yes, assemble the gratin up to one day in advance, cover, refrigerate, and bake when needed.

How do I prevent the sauce from curdling?
Cook the sauce gently, stirring constantly, and avoid boiling once the cheese is added.

What’s the best substitution for breadcrumbs?
Crushed crackers, extra Parmesan, or even crushed nuts work as great alternatives.

Is this dish gluten-free?
Use a gluten-free flour blend and skip the breadcrumbs to make it gluten-friendly.

Can I use plant-based milk?
Yes, unsweetened plant-based milk works well, though the texture and flavor may vary slightly.

---

Final Thoughts

Squash Gratin with Mornay Sauce is more than just a side dish—it’s a comforting masterpiece that brings warmth and joy to any meal. With its creamy layers, golden crust, and customizable options, it’s no wonder this recipe has become a favorite among home cooks. Whether you’re hosting a holiday gathering or simply craving something indulgent, this gratin delivers satisfaction in every bite.

So grab your ingredients, roll up your sleeves, and get ready to create a dish that will have everyone asking for seconds.

---

Recipe Card

Squash Gratin with Mornay Sauce

Yield: 6 servings
Prep Time: 20 minutes
Cook Time: 30 minutes
Total Time: 50 minutes

Ingredients:

• 2 pounds yellow squash or zucchini, thinly sliced
• 2 tablespoons butter
• 2 tablespoons all-purpose flour
• 1 ½ cups whole milk
• ½ cup grated Gruyère cheese
• ¼ cup grated Parmesan cheese
• ¼ teaspoon ground nutmeg
• Salt and black pepper to taste
• ½ cup breadcrumbs
• 1 tablespoon olive oil
• 1 tablespoon chopped fresh thyme or parsley (optional)

Instructions:

1. Preheat oven to 375°F (190°C). Grease a baking dish.
2. Steam or sauté squash until tender. Drain excess liquid.
3. Melt butter in a saucepan. Whisk in flour and cook for 1–2 minutes.
4. Gradually whisk in milk, stirring until thickened.
5. Stir in Gruyère, Parmesan, nutmeg, salt, and pepper.
6. Layer squash in the dish and pour sauce over it.
7. Mix breadcrumbs with olive oil and sprinkle on top.
8. Bake for 20–25 minutes until golden and bubbly. Garnish with herbs if desired.

Nutrition per Serving:
Calories: 210 | Sugar: 5g | Sodium: 280mg | Fat: 13g | Carbs: 15g | Protein: 9g

Enjoy!