Green Bean Casserole with Fried Shallots

Preparation

1. Step 1

   Melt 2 tablespoons butter in a large skillet over medium heat. Add onion, and cook, stirring occasionally, until beginning to soften, about 4 minutes. Add bell pepper and mushrooms, and cook, stirring occasionally, until softened and most of the liquid has evaporated, 8 to 10 minutes. Season with 1 teaspoon salt and 1/4 teaspoon black pepper. Remove from heat. Let cool completely.

   Step 2

   Bring a medium saucepan of water to a boil. Add beans; cook until bright green and just tender, 4 to 5 minutes. Drain, and plunge into an ice-water bath to stop cooking. Drain beans, and dry. Toss with mushroom mixture; set aside.

   Step 3

   Melt the remaining 4 tablespoons butter in a medium saucepan over medium heat. Add 1/4 cup flour; whisk constantly until mixture begins to turn golden, about 2 minutes. Pour in milk; continue whisking until mixture thickens, 4 to 6 minutes. Stir in cayenne, nutmeg, and remaining teaspoon salt and 1/4 teaspoon black pepper. Remove from heat; let cool completely, stirring occasionally. Pour over bean mixture, and toss.

   Step 4

   Butter a 13 × 9-inch baking dish. Spread half of the bean mixture into dish. Sprinkle with half of the Parmesan, and then top with remaining bean mixture. Combine remaining Parmesan and bread crumbs; sprinkle over top. Cover with foil, and refrigerate until ready to serve (up to 1 day); bring to room temperature before heating.

   Step 5

   Heat oil in a medium skillet over medium-high heat. Toss shallots with remaining 2 tablespoons flour. Fry shallots in 2 batches, turning frequently, until golden brown, about 3 minutes. Using a slotted spoon, transfer shallots to paper towels to drain; let cool completely. The shallots can be stored in an airtight container at room temperature up to 1 day.

   Step 6

   Preheat the broiler, with rack about 8 inches from heat. Cook casserole, covered, until mixture is bubbling and heated through, about 10 minutes. Uncover, and cook until top is golden brown, about 30 seconds. Remove from oven. Sprinkle with fried shallots. Serve immediately.