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Playing How to Make Potato, Green Bean and Mushroom Gratin | Milk Street's Chris Kimball

Milk Street's Chris Kimball, Rachael's favorite bow-tied cook, shares a Thanksgiving-ish dish for your holiday table: a rustic Italian vegetarian gratin of potatoes, green beans and mushrooms. 

"Polpettone alla Ligure is the Italian name for this rustic dish. The term polpettone translates as “meatloaf,” but in this case it refers to a mashup of vegetables baked into a casserole. Before baking, we top the vegetables with a mixture of panko and Parmesan for toasty crispness; after baking, the vegetables are set enough to be cut into neat squares. The gratin can be assembled, covered and refrigerated for up to six hours 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." —Chris 

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

Adapted from Milk Street Vegetables by Christopher Kimball. Copyright © 2021 by Christopher Kimball. Used with permission by Voracious. All rights reserved.

Milk Street Vegetables by Christopher Kimball

Milk Street Vegetables by Christopher Kimball


For more recipes from Chris Kimball's newest cookbook for the holidays or anytime, check out his Spicy Red Pepper Dip and Crispy Smashed Potatoes with Cilantro-Yogurt Hot Sauce.  


  • Cooking spray
  • 4 tablespoons salted butter, plus 2 tablespoons salted butter, melted
  • 1 pound Yukon Gold potatoes, peeled and sliced ¼ inch thick
  • Kosher salt and ground black pepper
  • 3 tablespoons extra-virgin olive oil
  • 2 medium shallots, finely chopped
  • 1 pound green beans, trimmed and cut into ¼-inch pieces
  • 8 ounces cremini mushrooms, trimmed and sliced about ¼ inch thick
  • 1 tablespoon minced fresh marjoram OR oregano
  • 2 large eggs
  • 3 ounces finely grated Parmesan cheese (1 ½ cups), divided
  • ½ cup panko breadcrumbs


Serves: 8


Heat the oven to 400°F with a rack in the middle position. Mist a 9-by-13-inch baking dish with cooking spray and set aside. 

In a 12-inch skillet over medium, melt 4 tablespoons butter. Add the potatoes and ½ teaspoon salt, then stir to coat. Add ½ cup water, then distribute the potatoes evenly. Cover and cook until a skewer inserted into the potatoes meet no resistance, 15 to 20 minutes, stirring once about halfway through. Transfer the potatoes and any liquid in the pan to a large bowl, then use fork to mash to the consistency of chunky mashed potatoes; set aside. 

Wipe out the skillet and set it over medium. Add the oil, shallots and ¼ teaspoon salt. Cook, stirring occasionally, until the shallots are softened but not browned, 5 to 6 minutes. Add the beans and mushrooms, then increase the heat to medium-high. Cook, stirring occasionally, until most of the liquid released by the mushrooms has evaporated and the beans are bright green but still crisp, about 5 minutes; the vegetables should not begin to brown. Stir in the marjoram and cook until fragrant, about 30 seconds. Transfer to the bowl with the potatoes and cool for about 10 minutes. 

In a medium bowl, whisk the eggs, 2 ounces (1 cup) of Parmesan and ½ teaspoon each salt and pepper. Add the egg mixture to the vegetable mixture and fold with a silicone spatula until combined. Transfer to the prepared baking dish and spread evenly. 

In a small bowl, combine the panko, melted butter and the remaining 1 ounce (½ cup) Parmesan, then stir until the panko is evenly moistened. Sprinkle evenly over the vegetables. Bake until golden brown and bubbling at the edges, about 30 minutes. Cool for about 15 minutes before serving.