Baked Haricots Verts with Fried Shallots

This from-scratch update of the classic green bean casserole eschews canned cream of mushroom soup and thicker green beans in favor of a fresh mushroom cream sauce and slender haricots verts. Fried shallots stand in for the iconic fried onion topping. You can fry the shallots and cook the beans up to 2 days ahead.

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  3 cups vegetable oil
  
  


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  3 large shallots, cut into 1/8-inch-thick rings (about 3 cups)
  
  


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  1 cup plus 3 Tbs. all-purpose flour
  
  


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  Kosher salt
  
  


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  2 lb. trimmed haricots verts, halved crosswise
  
  


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  2 oz. (4 Tbs.) unsalted butter
  
  


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  1-1/2 lb. mixed mushrooms (such as oyster, shiitake, and cremini), coarsely chopped (7 to 8 cups)
  
  


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  2 Tbs. medium sherry
  
  


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  2 cups lower-salt chicken broth
  
  


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  1 cup heavy cream
  
  


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  Freshly ground black pepper
  
  

Heat the oil in a 12-inch skillet over medium heat until shimmering hot.

Meanwhile, in a medium bowl, toss the shallots with 1 cup of the flour, separating the rings and coating them thoroughly. Working with a handful at a time, shake off the excess flour and fry, stirring occasionally with a slotted spoon, until golden, 1 to 2 minutes. Transfer to a paper-towel-lined plate and season lightly with salt. Discard the flour and frying oil and wipe out the skillet.

Bring an 8-quart pot of salted water to a boil. Boil the haricots verts until crisp-tender, about 4 minutes. Drain in a colander and cool under cold running water; pat dry. Position a rack in the center of the oven and heat the oven to 400°F.

Position a rack in the center of the oven and heat the oven to 400°F.

Melt the butter in the skillet over medium heat. Add the mushrooms and a pinch of salt; cook, stirring often, until most of the liquid has evaporated and the mushrooms are beginning to brown, about 7 minutes. Add the sherry and cook, stirring, until almost evaporated, about 1 minute. Sprinkle the remaining 3 Tbs. flour over the mushrooms and toss to coat. Slowly whisk in the broth and cream. Simmer, stirring occasionally, until the sauce thickens, about 10 minutes. Remove from the heat and stir in the haricots verts, 1 tsp. salt, and 1/2 tsp. pepper. Season to taste with more salt and pepper.

Transfer to a 9x13-inch baking dish and bake until bubbling around the edges, about 20 minutes. Gently stir the beans to redistribute the sauce, top with the shallots, and serve.