Ina Garten Zucchini Au Gratin

I used to treat zucchini like background noise—fine on the plate, never the star. But this gratin changed that.

Ina’s version takes humble summer squash and wraps it in caramelized onions, a whisper of nutmeg, and Gruyère that bubbles into gold. It’s rich but not heavy. And it taught me that vegetables only feel boring when we cook them without care.

Here’s how I made it Ina-level.

Why This Works So Well

It’s not just creamy and cheesy—it’s built with smart layering. The onions melt down first, bringing sweetness. Then the zucchini gets a two-stage cook: first tenderized, then roasted under breadcrumbs and Gruyère until golden.

The nutmeg seems subtle, but don’t leave it out. It deepens the flavor of the sauce and keeps everything from tasting one-note.

Ingredients That Pulled Weight

• Zucchini (2 lbs) – Slice it ¼ inch thick. Any thinner and it disappears; thicker, and it won’t cook through evenly.
• Yellow onions (1 lb) – Cooked low and slow until soft and sweet—not browned. They form the base of the dish.
• Unsalted butter (6 tbsp) – You need all of it. It builds the sauce and crisps the top.
• Kosher salt + black pepper – Season in layers. The zucchini needs it, the sauce needs it, and the topping needs it.
• Ground nutmeg (¼ tsp) – A small amount goes a long way. Warm, nutty, and surprisingly essential.
• All-purpose flour (2 tbsp) – Thickens the sauce without making it gluey.
• Hot milk (1 cup) – Helps the flour cook evenly and prevents lumps.
• Fresh breadcrumbs (¾ cup) – Absorb just enough butter to toast without turning soggy.
• Gruyère (¾ cup grated) – Melts into the topping and browns perfectly. I tried cheddar once—it overwhelmed the dish.

Swaps That Actually Worked

• Milk: I used half-and-half once. It was richer but not too heavy.
• Breadcrumbs: Panko worked in a pinch, but I had to toast them first to avoid a raw crunch.
• Cheese: A 50/50 mix of Gruyère and Comté was even better.

Lessons From My Oven

What Went Wrong	Why It Happens	How to Fix It
Watery texture	Zucchini wasn’t cooked long enough	Let it simmer uncovered to reduce
Curdled sauce	Cold milk added too fast	Use hot milk, and add slowly
Mushy zucchini	Covered too long or cut too thin	Cook uncovered after 10 minutes
Bland flavor	Didn’t season at each stage	Taste the onions, sauce, and mix separately

How to Make Ina Garten’s Zucchini Au Gratin

1. Preheat oven to 400°F.
2. Cook the onions in 6 tbsp butter over low heat for 20 minutes in a large sauté pan. They should be soft, not brown.
3. Add zucchini, cover, and cook 10 minutes. Uncover, season with salt, pepper, and nutmeg. Cook another 5 minutes.
4. Stir in flour, cook 2 minutes to eliminate raw taste.
5. Add hot milk, stir and simmer until it thickens into a creamy sauce.
6. Transfer to an 8×10-inch baking dish.
7. Top with breadcrumbs and grated Gruyère.
8. Dot with butter and bake 20 minutes, until bubbling and golden brown.

Tips I Always Use

• I slice the zucchini on a mandoline for uniform cooking—it’s faster and more consistent.
• I pre-toast the breadcrumbs if using store-bought, just to get that golden color right.
• I let the gratin sit for 10 minutes before serving. It sets the sauce and makes it easier to slice.

Freezing & Reheating

• Fridge: Keeps 2 days, tightly covered.
• Freezer: Freeze fully baked, well-wrapped. Reheat uncovered at 375°F for 20–25 minutes.
• Microwave: Works, but softens the topping—use the oven when you can.

Before You Make It…

Q: Can I make this ahead?
A: Yes. Assemble fully, refrigerate, then bake right before serving. You may need 5 extra minutes in the oven.

Q: Can I use other squash?
A: Yellow summer squash works great. Just keep the thickness the same.

Q: Can I skip the cheese?
A: You can—but it loses the gratin feel. Parmesan could work as a lighter topping.

Try More Recipes:

• Ina Garten Pork Souvlaki
• Ina Garten Marinated Flank Steak
• Ina Garten Skillet Cornbread