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Ligurian Potato, Green Bean and Mushroom Gratin

8 Servings

1 hour 20 minutes 50 minutes active, plus cooling

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Polpettone alla Ligure is the Italian name for this rustic, oven-baked dish. The term polpettone translates as “meatloaf,” but in this case, it refers to a mashup of vegetables baked into a casserole. In classic versions, the potatoes are cooked and pureed before cooked green beans, eggs and Parmesan cheese are mixed in. After baking, the vegetables are set enough to be cut into neat squares. For a more satisfying texture, we keep the potatoes on the chunky side, and for added savoriness, we supplement the beans with cremini mushrooms. Just before slipping the baking dish into the oven, we top the vegetables with a mixture of panko breadcrumbs and Parmesan for toasty crispness. If convenient, the gratin can be assembled, covered and refrigerated for up to six hours before baking, but keep the panko mixture separate. Just before baking, sprinkle with the topping and extend the cooking time by about 15 minutes. With a salad alongside, this dish is a satisfying vegetarian main, or offer it as a side to braises or roasts of almost any type.




Don’t overcook the mushrooms and beans when sautéing them, as they will continue to cook in the oven. Sauté the mushrooms until they give up their moisture and the beans are bright green but still quite crisp; they should not be browned.

1 hour 20 minutes

50 minutes active, plus cooling


  • 4

    tablespoons (½ stick) salted butter, plus 2 tablespoons salted butter, melted

  • 1

    pound Yukon Gold potatoes, peeled and sliced ¼ inch thick


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Kira H.
November 20, 2023
Pretty darn good
Really enjoyed the crust on the top of this caseral. Very delicious and flavor packed
Julia G.
November 27, 2022
Tasty comfort meal
Tasty dish. I used subbed to use things I had on hand - russets, red onion and some random mushrooms and dried oregano.
Joe B.
April 21, 2024
Good flavors, needs a sauce
I made this exactly as written. The flavors were very good and I can see how this would be a great side dish to a main course. As it was baking I noticed it was looking quite dry. So I made a garlic cream sauce and added a bit of pecorino to serve on the side. It was a great complement to the dish.
Alkuds J.

Made this today used a couple portobello mushrooms instead of cremini. Very tasty. Family loved it ! This recipe is a keeper! Thank you!

Kevin S.

The recipe could have easily included: slice the potatoes and the mushrooms with the slicing blade of a food processor. Mash the potatoes with a potato masher (which is, y'know, MADE FOR MASHING POTATOES - a fork is usually used for serving or eating). And finally - it would have been kind to indicate cutting 1 lb of green beans into 1/4" pieces is again, a task best done with the chopping blade of a food processor.

Sandra R.

You are right about a using a food processor but I did it by hand and it wasn't that time consuming. Like you, I also use a potato masher.

Sona E.

Some people, me included, don't have a food processor.

Barbara W.

I neglected to cut the string beans and in no way did the casserole suffer. Once baked, the string beans cut easily with the side of a fork.

Barbara W.

I just test drove this recipe in preparation for Thanksgiving. It was great. I made a different topping since I don't like cheese in Thanksgiving dishes. I have been looking for an alternative green bean casserole without Campbell's and this is it. I will be making this again in 3 days for the big day. Thank you.

Josh O.

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Cass and DJ L.

This recipe is delicious and went amazingly well with ribeye steaks.

Sandra R.

This was terrific. Really enjoyed it. Definitely a keeper. We had it with grilled turkey breasts. I think this would be a great side dish at Thanksgiving.

Laura B.

This is mind-blowing! Even my 22-month-old daughter loved it! I agree with Sandra R. about this being a great side dish for Thanksgiving. This is like a 3-star Michelin dish-version of green bean casserole. What amazing combination of ingredients, as it is just so savory! My husband is a fan, and he said this recipe is a keeper. I made quick work of the green beans and mushrooms by having them sliced in my food processor, same with the potatoes, too. Everything just came together as a perfect homogenous mixture. I had to take it out of the oven around the 20ish minute mark, as it was starting to bubble already, so make sure to check on it at about that time frame.

Tatiana R.

So with the shortages of random things, it was hard to find decent green beans. We bought a single bag of pre-trimmed ones (still had to trim them again because they didn't look so hot) that was only 12oz, rather than a pound. Also, got half a pound of mild Italian sausage because my son really doesn't like mushrooms. I split the beans and the shallots in two batches so I could make half of them with mushrooms and half with the sausage. I just had the left side of the baking dish filled with the mushroom-based mix and the right side with the sausage-based one. As you can see, with less beans and with 8oz of mushrooms AND 8oz of sausage, it's a different proportion of ingredients than in the recipe, but it all still looked right and tasted good. I wish there were more potatoes.

Merilee L.

Has anyone tried making this with mashed cauliflower instead of potatoes?

Linda W.

Pretty bland as written. Significantly better with triple the marjoram and addition of some Cajun seasoning.