Zucchini gratin is the kind of dish that feels indulgent without being heavy. It’s creamy, golden on top, and full of tender zucchini with just the right amount of garlic and cheese. You can make it for a simple weeknight dinner or bring it to a potluck and watch it disappear.
The best part? It uses basic ingredients and doesn’t require fussy techniques. If you’ve got a couple of zucchinis and a baking dish, you’re halfway there.
Ingredients
Method
-
Prep your oven and dish: Preheat the oven to 400°F (200°C). Grease a medium baking dish (about 9×9 inches or similar) with a bit of butter or oil.
-
Slice the zucchini: Cut into thin rounds, about 1/8-inch thick. Consistent thickness helps the gratin cook evenly and prevents soggy patches.
-
Sweat the zucchini (optional but recommended): Toss the slices with 1 teaspoon of salt and spread them on a clean kitchen towel.
Let sit for 10–15 minutes, then gently blot to remove excess moisture. This step keeps the gratin from becoming watery.
-
Soften the aromatics: In a skillet, warm the olive oil and butter over medium heat. Add the onion and a pinch of salt.
Cook 5–7 minutes until soft and translucent. Stir in the garlic for 30 seconds, just until fragrant.
-
Build the cream base: Pour in the heavy cream. Add a pinch of nutmeg, black pepper, and red pepper flakes if using.
Simmer for 2–3 minutes to slightly thicken and infuse the flavors. Remove from heat and stir in half of the Gruyère and half of the Parmesan until melted.
-
Layer the gratin: Arrange half the zucchini in the baking dish. Spoon over half the creamy mixture.
Sprinkle with a little thyme, salt, and pepper. Repeat with the remaining zucchini and cream.
-
Add the topping: In a small bowl, combine the remaining Gruyère and Parmesan with the bread crumbs. Sprinkle evenly over the top for a crisp, golden finish.
-
Bake: Place the dish on a baking sheet to catch drips.
Bake for 25–30 minutes, until the top is deeply golden and the edges are bubbling.
-
Rest before serving: Let the gratin sit for 10 minutes. This helps it set and makes serving cleaner.
-
Finish with herbs: Sprinkle fresh parsley or more thyme before bringing it to the table.
What Makes This Special
Zucchini gratin stands out because it balances comfort and freshness.
The zucchini stays light and slightly sweet, while the creamy sauce and cheese add richness and structure. A crisp, golden topping gives contrast in every bite. It’s also versatile: you can make it vegetarian, low-carb, or gluten-free with easy swaps.
Plus, it pairs with almost anything—roast chicken, grilled steak, salmon, or a leafy salad.
What You’ll Need
- Zucchini: 2 pounds (about 4–5 medium), thinly sliced
- Yellow onion: 1 small, thinly sliced (optional but adds flavor)
- Garlic: 2–3 cloves, minced
- Butter: 2 tablespoons
- Olive oil: 1 tablespoon
- Heavy cream: 1 cup (or half-and-half for a lighter version)
- Gruyère or Swiss cheese: 1 cup, shredded
- Parmesan: 1/2 cup, finely grated
- Bread crumbs or panko: 1/2 cup (use gluten-free if needed)
- Fresh thyme or parsley: 1–2 teaspoons, chopped
- Salt and black pepper: to taste
- Ground nutmeg: a pinch (optional but lovely with cream)
- Red pepper flakes: a pinch for gentle heat (optional)
Step-by-Step Instructions
- Prep your oven and dish: Preheat the oven to 400°F (200°C). Grease a medium baking dish (about 9×9 inches or similar) with a bit of butter or oil.
- Slice the zucchini: Cut into thin rounds, about 1/8-inch thick. Consistent thickness helps the gratin cook evenly and prevents soggy patches.
- Sweat the zucchini (optional but recommended): Toss the slices with 1 teaspoon of salt and spread them on a clean kitchen towel.
Let sit for 10–15 minutes, then gently blot to remove excess moisture. This step keeps the gratin from becoming watery.
- Soften the aromatics: In a skillet, warm the olive oil and butter over medium heat. Add the onion and a pinch of salt.
Cook 5–7 minutes until soft and translucent. Stir in the garlic for 30 seconds, just until fragrant.
- Build the cream base: Pour in the heavy cream. Add a pinch of nutmeg, black pepper, and red pepper flakes if using.
Simmer for 2–3 minutes to slightly thicken and infuse the flavors. Remove from heat and stir in half of the Gruyère and half of the Parmesan until melted.
- Layer the gratin: Arrange half the zucchini in the baking dish. Spoon over half the creamy mixture.
Sprinkle with a little thyme, salt, and pepper. Repeat with the remaining zucchini and cream.
- Add the topping: In a small bowl, combine the remaining Gruyère and Parmesan with the bread crumbs. Sprinkle evenly over the top for a crisp, golden finish.
- Bake: Place the dish on a baking sheet to catch drips.
Bake for 25–30 minutes, until the top is deeply golden and the edges are bubbling.
- Rest before serving: Let the gratin sit for 10 minutes. This helps it set and makes serving cleaner.
- Finish with herbs: Sprinkle fresh parsley or more thyme before bringing it to the table.
Storage Instructions
- Refrigerator: Cool completely, cover tightly, and refrigerate for up to 3 days.
- Reheat: Warm in a 350°F (175°C) oven for 15–20 minutes, loosely covered with foil. For a crisp top, uncover for the last 5 minutes.
- Freezer: Not ideal due to the high water content of zucchini, which can make the texture mushy after thawing.
If you must, freeze before baking and bake from frozen, adding extra time.
Benefits of This Recipe
- Simple ingredients, big flavor: You likely already have most of what you need.
- Great for using up zucchini: Perfect during peak season when zucchini is abundant and affordable.
- Flexible for diets: Easy to adapt for gluten-free or lower-carb eating.
- Make-ahead friendly: Assemble earlier in the day, then bake before serving.
- Crowd-pleaser: Creamy, cheesy, and comforting without being heavy.
Pitfalls to Watch Out For
- Watery gratin: Zucchini holds a lot of moisture. Salting and blotting the slices, or pre-sautéing them briefly, helps prevent excess liquid.
- Undercooked slices: Too-thick rounds can stay firm. Keep slices thin and uniform.
- Bland flavor: Don’t skimp on salt and pepper.
Zucchini is mild and needs seasoning in both the cream and the layers.
- Greasy top: Measure cheese and cream. Too much can make the dish heavy and oily.
- Overbrowning: If the top browns too quickly, tent loosely with foil for the final minutes.
Recipe Variations
- Lightened-Up: Use half-and-half instead of heavy cream and reduce cheese by one-third. Add a handful of chopped spinach for extra greens.
- Gluten-Free: Swap the bread crumbs for gluten-free panko or crushed gluten-free crackers.
- Keto/Low-Carb: Skip the bread crumbs and rely on extra Parmesan for a crisp top.
- Herb-Forward: Add fresh basil and chives to the cream.
Lemon zest brightens the whole dish.
- Cheese Twist: Try fontina, cheddar, or a mix of Gruyère and mozzarella for extra melt.
- Add Protein: Fold in cooked, crumbled bacon or diced ham between layers.
- Tomato Zucchini Gratin: Layer in thin tomato slices for a Provençal vibe; reduce cream slightly to balance the extra moisture.
Can I Make This Ahead?
Yes. Assemble the gratin up to the point of baking, cover, and refrigerate for up to 24 hours. Add 5–10 minutes to the baking time if it goes into the oven cold.
How Do I Prevent It From Getting Watery?
Salt and blot the zucchini before layering.
You can also sauté the slices for 3–4 minutes to release moisture, then drain on paper towels. Avoid covering the dish while baking, so steam escapes.
What’s the Best Cheese for Gratin?
Gruyère is classic for its nutty melt and slight sweetness. Parmesan adds salty depth.
Swiss, fontina, or mild cheddar also work. Aim for one melty cheese and one sharp, flavorful cheese.
Can I Use Yellow Squash Instead?
Absolutely. Yellow squash behaves similarly to zucchini.
You can use one or the other, or a mix for color and flavor variety.
Is There a Dairy-Free Option?
Use a rich, unsweetened plant-based cream (like cashew cream or full-fat coconut milk) and a good melting vegan cheese. Taste and adjust seasoning, as dairy-free cheeses vary in saltiness.
What Should I Serve With Zucchini Gratin?
It pairs well with roast chicken, seared salmon, grilled steak, or a simple green salad. For a vegetarian meal, add crusty bread and a tomato salad on the side.
Can I Add Potatoes?
Yes.
Thinly slice a small russet or Yukon Gold and layer it with the zucchini. Par-cook the potato slices in salted water for 5 minutes so everything finishes at the same time.
Wrapping Up
Zucchini gratin is a reliable, cozy dish that turns a humble vegetable into something special. With a creamy base, a crisp top, and a few smart techniques, it’s both easy and impressive.
Keep it classic or try a variation based on what you have. Either way, you’ll end up with a bubbly, golden pan that’s hard to resist. Keep this one in your regular rotation—especially when zucchini season hits its stride.
Printable Recipe Card
Want just the essential recipe details without scrolling through the article? Get our printable recipe card with just the ingredients and instructions.