Zucchini and Yellow Squash Au Gratin

Golden, bubbling, and irresistibly creamy—this Zucchini and Yellow Squash Au Gratin is summer comfort food at its finest. Tender slices of green and yellow squash are layered and bathed in a garlicky cream sauce, then topped with a generous blanket of melted cheese that crisps up beautifully in the oven. It’s the kind of dish that steals the spotlight on any dinner table, whether served as a side or a standalone star.

Behind the Recipe

This recipe came about one late summer evening when the garden was overflowing with squash and the fridge begged for something hearty but fresh. Combining the creamy indulgence of a classic gratin with the light, vibrant flavor of summer squash turned out to be the perfect match. It’s simple, elegant, and always a crowd-pleaser—especially when the cheese on top turns golden and bubbly.

Recipe Origin or Trivia

The word “gratin” originates from French cuisine, referring to a dish that’s baked with a browned crust, typically of breadcrumbs or cheese. While potatoes are the usual star in classic gratins like Gratin Dauphinois, vegetables like zucchini and yellow squash bring a fresh, seasonal twist. In Provençal cooking, you’ll often find summer vegetables used this way—layered, baked, and topped with cheese or breadcrumbs for a rustic and satisfying result.

Why You’ll Love Zucchini and Yellow Squash Au Gratin

Versatile: Pairs with grilled meats, roast chicken, or makes a fantastic vegetarian entrée.

Budget-Friendly: Uses seasonal produce and pantry staples.

Quick and Easy: Simple prep and just 30 minutes in the oven.

Customizable: Add herbs, spices, or different cheeses to suit your taste.

Crowd-Pleasing: Creamy, cheesy, and packed with flavor—no one turns it down.

Make-Ahead Friendly: Assemble early, bake when ready.

Great for Leftovers: Reheats well and makes an excellent lunch the next day.

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Chef’s Pro Tips for Perfect Results

For a gratin that’s rich but not watery, here’s what you need to know:

• Salt the squash slices and let them sit for 10 minutes to draw out excess moisture.
• Use a mandoline for even, thin slices that cook evenly.
• Layer cheeses like Parmesan and Gruyère for depth of flavor.
• Bake uncovered to allow the top to brown beautifully.
• Let it rest for 5–10 minutes after baking for a firmer, sliceable texture.

Kitchen Tools You’ll Need

A few basic tools will make this recipe a breeze:

• Mandoline or Sharp Knife: For slicing squash thinly and evenly.
• Large Mixing Bowl: To toss squash in seasoning and cream.
• Oven-Safe Baking Dish: A 9×9 or oval gratin dish works well.
• Cheese Grater: Freshly grated cheese melts better and tastes richer.
• Measuring Cups and Spoons: For precise flavor balance.
• Foil (optional): To prevent over-browning if baking longer.

Ingredients in Zucchini and Yellow Squash Au Gratin

These humble ingredients come together to create something surprisingly decadent:

1. Zucchini: 2 medium, thinly sliced—tender with a mild, fresh flavor.
2. Yellow Squash: 2 medium, thinly sliced—adds color and a slightly sweet note.
3. Heavy Cream: 1 cup for a rich, silky sauce that binds everything.
4. Garlic: 3 cloves, minced for aromatic depth.
5. Parmesan Cheese: ½ cup, grated—adds nutty sharpness.
6. Gruyère Cheese: 1 cup, grated—melts beautifully and brings bold flavor.
7. Salt: 1 teaspoon to season and draw out moisture from squash.
8. Black Pepper: ½ teaspoon for gentle spice.
9. Thyme Leaves: 1 teaspoon fresh (or ½ teaspoon dried) for herbal brightness.
10. Olive Oil or Butter: 1 tablespoon for greasing the dish.

Ingredient Substitutions

No need to make a store run—here are some smart swaps:

Heavy Cream: Half-and-half or whole milk with a tablespoon of flour.
Gruyère Cheese: Swiss, sharp white cheddar, or fontina.
Parmesan Cheese: Pecorino Romano or Asiago.
Yellow Squash: More zucchini or thinly sliced eggplant.
Fresh Thyme: Dried thyme or fresh basil.

Ingredient Spotlight

Gruyère Cheese: Known for its creamy melt and nutty flavor, Gruyère is the perfect cheese for gratins, lending richness without overpowering the veggies.

Zucchini: With its high water content and soft texture, zucchini soaks up the garlicky cream while adding a fresh, garden-like taste to every bite.

Instructions for Making Zucchini and Yellow Squash Au Gratin

Time to turn fresh squash into cheesy, bubbling goodness. Follow these steps for success:

1. Preheat Your Equipment:
   Preheat your oven to 375°F (190°C). Grease a 9×9 baking dish with butter or olive oil.
2. Combine Ingredients:
   In a bowl, toss zucchini and yellow squash slices with salt. Let sit 10 minutes, then pat dry with paper towels to remove excess moisture.
3. Prepare Your Cooking Vessel:
   In another bowl, mix heavy cream, minced garlic, black pepper, and thyme. Stir in half of the Parmesan and Gruyère.
4. Assemble the Dish:
   Layer squash slices in the dish, slightly overlapping. Pour cream mixture evenly over layers. Sprinkle remaining cheese on top.
5. Cook to Perfection:
   Bake uncovered for 30–35 minutes, or until bubbly and golden brown on top.
6. Finishing Touches:
   Let rest 5–10 minutes to set before slicing. Garnish with extra thyme or parsley if desired.
7. Serve and Enjoy:
   Serve warm as a side dish or vegetarian main—savor every creamy, cheesy bite.

Texture & Flavor Secrets

The top gets perfectly golden and crisp while the squash underneath softens into tender layers soaked with garlic and herbs. Gruyère adds complexity, while the cream binds it all into a luxurious, melt-in-your-mouth medley. The hint of thyme cuts through the richness, keeping it light enough to enjoy all summer long.

Cooking Tips & Tricks

• Use fresh squash, not frozen, to avoid excess moisture.
• Salt and drain squash before assembling for firmer texture.
• Use multiple cheese types for balanced melt and flavor.
• Slice squash as evenly as possible for consistent cooking.

What to Avoid

• Don’t skip salting the squash—it’s key to avoiding a watery gratin.
• Avoid using pre-shredded cheese—it contains starches that affect melt quality.
• Don’t overbake or the squash will turn mushy.
• Don’t crowd the layers—spread them evenly to allow even baking.

Nutrition Facts

Servings: 6
Calories per serving: 240
Note: These are approximate values.

Preparation Time

Prep Time: 15 minutes
Cook Time: 35 minutes
Total Time: 50 minutes

Make-Ahead and Storage Tips

You can slice and salt the squash ahead of time or fully assemble the dish and refrigerate up to 24 hours before baking. Leftovers keep well in the fridge for 3 days and reheat beautifully in the oven or microwave. Avoid freezing, as squash may become watery.

How to Serve Zucchini and Yellow Squash Au Gratin

Serve warm as a hearty side dish with roasted chicken, steak, or grilled fish. Or let it shine on its own with a side salad and crusty bread. It also makes a wonderful potluck or holiday addition.

Creative Leftover Transformations

• Veggie Quesadillas: Fold into tortillas with cheese and grill.
• Baked Eggs: Scoop into a ramekin, crack in an egg, and bake.
• Savory Crepes: Wrap in thin crepes and drizzle with extra cream sauce.
• Veggie Bowl: Serve over quinoa or rice with a drizzle of olive oil.

Additional Tips

• Add breadcrumbs or crushed crackers on top for a crunchy finish.
• Drizzle with truffle oil before serving for an upscale touch.
• Use a mix of green and yellow squash for color contrast.
• For spice, add a pinch of cayenne or red pepper flakes to the cream.

Make It a Showstopper

Arrange the squash slices in a spiral or layered fan for a stunning presentation. Finish with a broil for extra golden color and serve in a beautiful ceramic gratin dish straight from the oven to table.

Variations to Try

• Tomato Twist: Add thin slices of tomato between layers.
• Bacon Lovers: Mix in cooked, crumbled turkey bacon.
• Herb Explosion: Add chopped rosemary, chives, or basil.
• Cheesy Overload: Top with mozzarella or fontina for extra gooeyness.
• Low-Carb: Use almond milk and nutritional yeast for a lighter version.

FAQ’s

Q1: Can I make this dairy-free?
A1: Yes, use coconut cream or a dairy-free alternative and vegan cheese.

Q2: How do I keep it from being watery?
A2: Salt the squash first and pat it dry to remove excess moisture.

Q3: Can I use just one type of squash?
A3: Absolutely—zucchini or yellow squash alone work just fine.

Q4: Can I freeze it?
A4: Freezing is not recommended, as squash becomes watery upon thawing.

Q5: What cheeses work best?
A5: Gruyère, Parmesan, cheddar, or fontina all melt beautifully.

Q6: How thick should the slices be?
A6: About ⅛ inch for even cooking and texture.

Q7: Can I add breadcrumbs?
A7: Yes, sprinkle on top before baking for a crispy crust.

Q8: How long does it stay fresh?
A8: Up to 3 days in the fridge in an airtight container.

Q9: Can I prepare it ahead of time?
A9: Yes, assemble up to a day in advance and bake when ready.

Q10: Is it vegetarian?
A10: Yes, just be sure to use vegetarian cheese if needed.

Conclusion

Zucchini and Yellow Squash Au Gratin is everything you want in a summer dish—light yet luscious, simple yet elegant. It’s a celebration of seasonal produce, comforted by cream and cheese, and baked to golden perfection. Whether it’s a side or the star, this dish is destined to become a favorite on your table.

Watch How To Make Zucchini and Yellow Squash Au Gratin