Zucchini and Potato al Forno layers paper-thin zucchini, potatoes, and onion, finishes with a seasoned breadcrumb topping, and bakes until golden. This flavorful vegetable casserole makes an excellent side or a satisfying vegetarian main.
Old school contorni
Italian vegetable side dishes, or contorni, are timeless. Whether it’s a classic Italian potato casserole or this Zucchini Potato al Forno, these simple layered dishes evoke family meals and comfort.
My grandmother often made vegetables layered with breadcrumbs and cheese. It’s the kind of humble cooking that becomes special when you recreate it for your own table.
Zucchini and potato al forno works beautifully as a side for roasted or grilled meats and pairs particularly well with grilled chicken thighs, stuffed pork chops, or meatballs in a tomato sauce. It’s also hearty enough to serve as a vegetarian main.
Recipe Ingredients
All main ingredients are pictured below; notes follow to help you choose and prepare them.
- Zucchini. Choose medium-sized, firm zucchini and slice thinly.
- Potatoes. Yukon Golds hold their shape well; russets are usable but will be flourier.
- Onion. Yellow or white onions work best; slice thinly to match the vegetables.
- Breadcrumbs. Use store-bought plain or Italian-style breadcrumbs, or make your own for the topping.
- Cheese. Parmigiano Reggiano is used here; domestic Parmesan or Pecorino Romano are fine substitutions (Pecorino is saltier).
- Oregano. Sicilian oregano is ideal for baked vegetables, but any dried oregano will do.
See the recipe card for exact ingredient amounts and the full ingredient list.
How to make zucchini potato al forno
Follow these steps to build and bake the dish.
- Combine breadcrumbs, 1 teaspoon oregano, 3 tablespoons grated Parmigiano Reggiano, red pepper flakes, 3 tablespoons extra virgin olive oil, and minced garlic in a bowl; set aside.
- Using a mandoline with a guard or a very sharp knife, slice potatoes, onion, and zucchini about 1/8-inch thick.
- Lightly drizzle extra virgin olive oil in a 9×13 baking dish. Arrange a single overlapping layer of potato slices across the bottom.
- Add an overlapping layer of onion, drizzle with olive oil, and season with salt, oregano, and a sprinkle of Parmesan. Repeat for an additional potato and onion layer if desired.
- Bake at 425°F on the middle rack for 30 minutes. Reduce the oven to 375°F and check the potatoes; if still very firm, bake another 10 minutes until nearly fork-tender.
- Arrange the zucchini in overlapping layers on top of the potatoes and onions.
- Scatter the seasoned breadcrumb mixture over the zucchini and drizzle with olive oil to moisten the crumbs.
- Bake at 375°F for about 30 minutes, or until the potatoes are fully fork-tender and most liquid has evaporated. If the crumbs need more color, broil 1–2 minutes while watching closely to avoid burning. Let the dish rest at least 10 minutes before serving to allow juices to settle.
Top tips
- Slicing. A mandoline speeds things up but always use the guard and follow safety instructions. If you don’t have one, a sharp knife works—just aim for uniform thin slices.
- Cook time. Thicker slices and extra layers increase baking time. Adjust accordingly and bake until the bottom potatoes are tender.
- Finishing. A short broil at the end nicely browns the breadcrumbs—watch carefully. The casserole tastes great after resting and is especially enjoyable near room temperature.
More Italian vegetable dishes
If you enjoy baked vegetables with crunchy breadcrumb toppings, try other classics such as Italian zucchini casserole, baked cauliflower with cheese and breadcrumbs, or asparagus with cheese and breadcrumbs.
- Italian zucchini casserole
- Baked cauliflower with cheese and breadcrumbs
- Asparagus with cheese and breadcrumbs
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Zucchini Potato al Forno
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Ingredients
- 2 1/2 pounds yellow potatoes thinly sliced (1/8″ thick)
- 1 medium onion thinly sliced (1/8″ thick)
- 3 medium zucchini thinly sliced lengthwise (1/8″ thick)
- salt to taste
- 2 teaspoons Sicilian oregano
- 1/4 cup grated Parmigiano Reggiano
- 1/2 cup extra virgin olive oil divided
Seasoned breadcrumb mixture (mix together)
- 1 cup breadcrumbs
- 1 teaspoon Sicilian oregano
- 3 tablespoons grated Parmigiano Reggiano
- 1/2 teaspoon crushed hot red pepper flakes
- 3 tablespoons extra virgin olive oil
- 3 cloves garlic minced
Instructions
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Preheat the oven to 425°F and set the rack to the middle position. Mix the seasoned breadcrumb ingredients and set aside.
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Drizzle a little olive oil in a 9×13 baking dish. Place a single overlapping layer of potato slices, then add a layer of onion. Drizzle more olive oil and season each layer with salt, oregano, and a bit of Parmesan. Repeat for a second potato/onion layer if desired. Bake 30 minutes.
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Reduce oven temperature to 375°F. Check the potatoes; if still quite firm, return to the oven for 10 more minutes until nearly fork-tender.
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Layer the zucchini on top, overlap as you go, then sprinkle the seasoned breadcrumbs over the zucchini and drizzle with olive oil. Bake another 30 minutes or until potatoes are tender.
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Most liquid should be gone at this point. If the topping needs color, broil 1–2 minutes while watching closely. Let rest at least 10 minutes before serving.
Notes
- Baking dish. A wide, shallow dish with two layers cooks faster and more evenly than a deep dish with multiple layers, though both work.
- Seasoning. Season between layers to distribute flavor evenly; adjust amounts if you add layers.
- Cook time. Times vary with slice thickness and number of layers—bake until the bottom potato layer is tender and most liquid has evaporated.
- Brown to finish. Broil 1–2 minutes for extra browning, watching carefully to prevent burning.
- Leftovers. Refrigerate up to 3 days; reheat in the oven or microwave.
Nutrition
Nutrition information is an approximation.