This green bean casserole is a fresh spin on a beloved classic

I was surprised to learn that Dorcas Reilly, Campbell’s Soup home economist who created the Green Bean Casserole in 1955, developed it as an everyday side dish, according to the company’s website. It wasn’t until the 1960s, when the recipe was printed on the cream of mushroom soup label, that it took off as a Thanksgiving favorite, one that is now shared on more than 20 million holiday tables each year.

I am a fan of Reilly’s original recipe and applaud her innovation. But while Reilly’s canned soup-centric side offers a familiar nostalgia, making the dish from scratch with fresh ingredients reveals its real potential, elevating it immeasurably from the shortcut, everyday food she intended it to be. For such a special holiday, it’s well worth the modest extra effort involved.

Start by frying sliced shallots in olive oil until they are golden and crisp. These eventually top the casserole (instead of the usual canned fried onions), while the shallot-infused oil is used to sauté a heap of meaty mushrooms. I like to use what is sold as “wild” or “gourmet” mushroom mix, but any combination and variety — even regular button mushrooms — works. Amplifying the quantity of mushrooms from the little bits in the original ratchets up the umami, elegance and nutrients in the dish.

Use the same pot to make the sauce, which I lighten by using milk instead of cream. The key is to combine the flour with cold milk until it is dissolved, then bring the mixture to a boil, whisking all the while.

Once at a boil, the slurry gets simmered until it is thick and creamy, then is seasoned with Parmesan, parsley, nutmeg, salt and pepper. Combine the sauce with lightly steamed green beans and the sautéed mushrooms, then transfer everything to a baking dish, top with the crispy shallots and more Parmesan, and bake.

The finished dish feels familiar yet enhanced, tasting of the fresh ingredients it’s made of — crisp-tender green beans and meaty mushrooms in a fragrant creamy sauce, with a crunch from the shallots. It offers a refreshing new perspective on just how delightful the retro Thanksgiving favorite can be.

• Ellie Krieger is a registered dietitian nutritionist and cookbook author who hosts public television’s “Ellie’s Real Good Food.” Learn more at www.elliekrieger.com.

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Green Bean Casserole With Crispy Shallots

¼ cup olive oil

1 cup thinly sliced shallots, separated into rings (from 3 medium shallots)

1½ pounds green beans, trimmed

1 pound mixed fresh mushrooms, such as cremini, oyster and shiitake, stemmed, as needed, and sliced

6 large garlic cloves, minced or finely grated

1 tablespoon chopped fresh thyme leaves

3 cups cold milk (any fat level, regular or nondairy)

3 tablespoons all-purpose flour

⅓ cup plus 2 tablespoons (1¼ ounces) grated parmesan cheese, divided

½ cup finely chopped fresh flat-leaf parsley

½ teaspoon fine salt

½ teaspoon freshly ground black pepper

¼ teaspoon ground nutmeg

In a small (8-inch) skillet over medium-high heat, heat the oil until very hot but not smoking. Set a large plate lined with paper towels nearby.

Working in four batches to avoid overcrowding, add about ¼ cup of the shallots to the hot oil, arranging them in a single layer, and cook, stirring occasionally, until golden brown and crisp, about 2 minutes. Using a slotted spoon or spider, transfer to the prepared plate and drain. Remove from the heat, reserving the oil in the skillet.

In a large pot over high heat, bring a few inches of water to a boil. Put the green beans in a steamer insert that fits in the pot, and gently lower the steamer into the pot. Cover and steam for 3 minutes, until they are a brighter green and still crisp. (Alternatively, microwave them in a covered, microwave-safe bowl, with 2 tablespoons of water, on HIGH for 3 minutes.) Drain, and transfer to a large bowl.

Wipe the pot dry and return to medium-high heat. Add 2 tablespoons of the reserved shallot oil and heat until shimmering. Add the mushrooms and cook, stirring occasionally, until they exude their liquid and it evaporates, and they start to brown, about 12 minutes. Add the garlic and thyme, and cook, stirring, until aromatic, about 30 seconds. Transfer the mushroom mixture to the bowl with the green beans, and reduce the heat to medium but keep the skillet on the stove.

In a small bowl, whisk together the milk and flour until well combined, and add to the skillet. Whisking constantly, bring the mixture to a simmer. Reduce the heat to medium-low and cook, whisking occasionally, until the mixture thickens and has the texture of a thick gravy, about 10 minutes. Remove from the heat, and stir in ⅓ cup (1 ounce) of the Parmesan, the parsley, salt, pepper and nutmeg until combined. Add the milk mixture to the green beans and mushrooms, and toss to coat.

Grease a 2-quart baking dish with about ½ tablespoon of the reserved shallot oil. Transfer the green bean mixture to the prepared dish, spreading it in an even layer.

Position a rack in the middle of the oven and preheat to 375°F. Sprinkle the top of the casserole with the remaining 2 tablespoons of Parmesan, followed by the crispy shallots. Bake for about 20 minutes, or until the casserole is golden on top and bubbling in places. Let sit for a few minutes before serving.

Servings: 8 (makes about 8 cups)

Substitutions: For milk, use half-and-half or cream. For shallots, use onions, any type. For Parmesan cheese, use pecorino Romano or grana Padano. For fresh thyme, use 1½ teaspoons dried. Gluten-free? Use a gluten-free all-purpose flour mix. For fresh green beans, use frozen green beans. For homemade crispy shallots, use store-bought fried onions or shallots, such as French’s.

Make ahead: The crispy shallots can be prepared and refrigerated in an airtight container up to 1 day in advance. The green bean casserole can be assembled, covered and refrigerated up to 1 day in advance. Bring to room temperature before baking.

Nutritional information per serving (1 cup, using low-fat milk): 185 calories, 10 g fat, 2 g saturated fat, 19 g carbohydrates, 202 mg sodium, 8 mg cholesterol, 9 g protein, 4 g fiber, 10 g sugar.

— Ellie Krieger