This potato and trombetta zucchini casserole builds on the Neapolitan potato gateau and adds a layer of tender zucchini to make it a complete meal. I found it in a copy of Cucina Italiana from the 70s, and it belongs at the centre of a large dinner table.
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A Gateau with Vegetables
The potato gateau is one of the great Neapolitan casserole dishes.
My mother made it often.
This recipe comes from a copy of Cucina Italiana from the 70s.
It takes that same base and places a layer of trombetta zucchini on top.
A few slices of pancetta scattered over the top add enough savour to carry the dish as a main.
You can read more about trombetta zucchini in my Amazing Zucchini Trombetta Albenga article.
Regular zucchini works well as a substitute.
Buy small ones because they contain less water and have fewer seeds, which matters when layering them over a potato base.
Other recipes you can make with trombetta zucchini are my pasta with ricotta and zucchini and my pasta with zucchini and prawns.
For more Italian baked casserole recipes, you can try my Eggplant Parmigiana, Rice Timbale, Zucchini Mushroom Quiche with Bacon, and Baked Pasta Anelletti.
The Ingredients
- Potatoes: Use floury potatoes that mash well. They form the base of the casserole and need enough body to hold their shape when spread into the dish.
- Trombetta zucchini (trombette): The long, pale zucchini from Liguria with dense flesh and very few seeds. Their low water content makes them well suited to a layered dish like this. If you use regular zucchini, choose the smallest you can find.
- Butter: Used in two stages. A small amount goes into the pan for cooking the zucchini. A larger amount enriches the mashed potato base.
- Shallots (optional): If using, cook gently in butter and oil without browning before the zucchini go in. They keep the flavour of the zucchini layer mild and sweet.
- Emmental and Parmigiano: Both go into the potato base. Use shredded Emmental - it melts evenly into the potato and adds creaminess. The Parmigiano brings sharpness and forms a light crust on the surface during baking.
- Pancetta (thinly sliced): Scattered between the zucchini rounds before baking. It adds a layer of savour that pushes this from a side dish into a main. Skip it if you prefer to keep the dish vegetarian.
- Egg yolks: They bind and enrich the mashed potato mixture.
- Breadcrumbs: For dusting the buttered baking dish. They prevent the potato base from sticking and give the outside edges a thin, lightly crisped crust.
- Olive oil: Used together with butter to sauté the zucchini.
- Nutmeg, salt, and pepper: The seasoning that runs through both layers, the zucchini and the potato base.
Find the measurements in the recipe card below.
How to Make Potato and Trombetta Zucchini Casserole
- Place the unpeeled potatoes in a pot of cold water and boil until cooked through.
- Wash, dry, and slice the trombetta zucchini into thin rounds.
- Melt 20 g of butter with the olive oil in a pan over low heat.
- If using shallots, finely chop them and cook in the butter and oil without letting them brown before adding the zucchini.
- Add the zucchini rounds, season with salt, freshly ground pepper, and a pinch of nutmeg, and cook for a few minutes.
- Continue to stir-fry the zucchini over medium heat until cooked through, about 20 minutes.
- Drain, peel, and pass the hot potatoes through a food mill with a medium disc into a bowl. Mix in the butter cut into pieces, the shredded Emmental, the egg yolks, the grated Parmigiano, a pinch of nutmeg, and salt. Stir vigorously after each addition.
- Grease a round metal baking dish ( 9 in - 23 cm diameter) with butter and dust it with breadcrumbs. A round metal dish gives a better crust on the bottom; a ceramic dish works too. Spread the potato mixture evenly over the bottom and slightly up the sides. Dust the surface with additional grated Parmigiano, then distribute the cooked zucchini and their cooking juices over the top. Arrange pieces of pancetta between the zucchini.
- Bake in a preheated oven at 200°C for about 20 minutes on a lower rack. Placing the dish on the lower rack keeps the zucchini rounds from over-browning while the potato base turns golden. Serve hot.
Serving Suggestions
Serve this casserole hot, straight from the baking dish, as the main course of a family dinner or a large gathering.
It can also be served as a side dish alongside a roasted meat such as porchetta romana or braciolette.
Frequently Asked Questions
What are trombetta zucchini and where do I find them?
Trombetta zucchini, also called Zucchini Trombetta d'Albenga, come from Liguria. They are long and thin, with all their seeds concentrated at the end, which makes them less watery and more consistent than regular zucchini. You find them in Italian and French Riviera markets during summer. As they become very popular, you may find them soon in your local specialized market. I have written more about them in my pasta with ricotta and zucchini post.
Can I use regular zucchini instead of trombetta?
Yes, you can substitute with regular zucchini. Buy small ones so they do not have too many seeds and their water content is lower.
Can I use a different vegetable instead of zucchini?
Yes. You can substitute the zucchini with other vegetables such as spinach, tomatoes, artichokes, or onion. A soffritto of onion, celery, and carrot stir-fried in butter also works well. For more ideas, check my pasta with ricotta and zucchini post.
Can I skip the pancetta?
Yes, you can skip the pancetta. The dish works well without it if you prefer to keep it vegetarian.
What type of potatoes should I use?
Use starchy potatoes that mash well, like Russet or Yukon Gold. Avoid waxy varieties such as red or new potatoes - they resist mashing and will not give the base the right texture.
Can I make this casserole ahead of time?
Yes. You can assemble the casserole ahead of time, cover it, and refrigerate it. Bake it just before serving.
Can I freeze this casserole?
You can but I would not recommend freezing this casserole as in my opinion cooked potatoes don't freeze well.
Can I use a different cheese instead of Emmental?
Yes. You can use another melting cheese in place of Emmental. Gruyère is the closest substitute and gives a similar result.
More casserole recipes
More recipes with zucchini
If you are making any of this Potato zucchini casserole, leave your comment below I would like to hear from you. You can find more delicious ideas if you FOLLOW ME on Facebook, YouTube, Instagram or sign up to my newsletter.
Potato and Trombetta Zucchini Casserole (Teglia di Patate e "Trombette")
Verified Culinary AuthorityIngredients
- 1 lb Potatoes
- 1 lb zucchini
- 3.5 oz Butter some for sautéing, the rest for potato purée, plus extra for the pan
- 1 Shallots optional
- ¼ Cup Shredded Emmental cheese
- ¼ Cup Grated Parmigiano cheese plus extra for dusting
- ¼ Pancetta
- 2 Eggs yolks
- 2 tablespoon Breadcrumbs as needed
- 2 tablespoon Olive oil
- 1 pinch Nutmeg
- 2 teaspoon Salt
- Pepper
Instructions
Prepare the vegetables
- Place the unpeeled potatoes in cold water and boil until cooked through.
- Wash, dry, and slice the trombetta zucchini into thin rounds.
- Melt 20 g of butter with 2 tablespoons of olive oil in a pan over low heat.
- If using shallots, finely chop them and cook in the butter and oil without letting them brown before adding the zucchini.
- Add the zucchini rounds, season with a pinch of salt, freshly ground pepper, and nutmeg, and cook for a few minutes.
- Continue to stir-fry over medium heat until cooked through, about 20 minutes.
- Prepare the potato purée:
- Drain, peel, and mash the hot potatoes using a food mill with a medium disc into a bowl.
- Mix in the remaining butter, the shredded Emmental, the egg yolks, the grated Parmigiano, a pinch of nutmeg, and salt. Stir vigorously after each addition.
Assemble the dish:
- Grease a round metal baking dish with butter and dust with breadcrumbs. A round metal dish gives a better crust on the bottom; a ceramic dish also works.
- Spread the potato mixture evenly over the bottom and slightly up the sides.
- Dust with additional grated Parmigiano, then distribute the cooked zucchini along with its cooking juices over the top.
- Intersperse with pieces of sliced pancetta.
- Bake in a preheated oven at 200°C for about 20 minutes on a lower oven rack so the zucchini rounds do not over-brown while the potato base turns golden. Serve hot.
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