Description

• 1 bunch broccoli (1 1/2 pounds), cut into florets (about 5 cups)
• Kosher salt and freshly ground pepper
• 4 tablespoons unsalted butter, plus 2 tablespoons melted
• 1 1/2 pounds boneless, skinless chicken breast, cut crosswise into 1/2-inch-thick strips
• 1 small onion, finely chopped (1 cup)
• 8 ounces cremini mushrooms, sliced (about 2 1/2 cups)
• 3 tablespoons unbleached all-purpose flour
• 3 cups whole milk, room temperature
• 9 ounces shredded medium-sharp cheddar (3 cups)
• 2 teaspoons Dijon mustard
• 1 teaspoon Worcestershire sauce
• 1/8 teaspoon cayenne pepper
• 1/2 cup sour cream
• 1 cup panko breadcrumbs
• Cooked egg noodles or steamed white rice, for serving

• Step 1

  Preheat oven to 400 degrees. In a large straight-sided skillet, simmer 1/2 cup water over medium-high heat, then add broccoli and a pinch of salt. Cover, reduce heat to medium-low, and cook until crisp-tender, about 6 minutes. Drain well, then transfer to a large bowl; set aside. Wipe out skillet.

• Step 2

  Pat chicken dry; season with salt and pepper. Melt 2 tablespoons butter over medium-high heat. Add half the chicken and cook, turning once, until browned and cooked through, about 4 minutes. Transfer to a plate. Repeat with remaining chicken; set aside.

• Step 3

  3. In same skillet, melt 2 tablespoons butter, then add onion and mushrooms. Cook, stirring occasionally, until tender and starting to brown, 6 to 7 minutes. Add flour and cook, stirring, 30 seconds. Slowly add milk, reduce heat to medium, and cook, stirring constantly, until mixture is thick enough to coat the back of a spoon, about 9 minutes. Add 2 cups cheese, Dijon, Worcestershire, cayenne, and sour cream; stir until combined. Season with salt and pepper. Add cheese sauce to bowl with broccoli, followed by chicken and accumulated juices; toss to combine. Transfer to a 2 1/2-quart baking dish.

• Step 4

  In a small bowl, combine 2 tablespoons melted butter, panko, and remaining 1 cup cheese. Sprinkle over broccoli-and-chicken mixture. Bake until bubbly and golden, 20 to 25 minutes. Let cool 15 minutes, then serve over noodles or rice.