- cooking spray
- 4 skinless, boneless chicken breast halves
- 1 head broccoli, cut into small pieces
- 3 tablespoons butter
- 3 tablespoons all-purpose flour
- 1/2 cup chicken stock
- 1/2 cup milk
- 1/2 cup chopped onion
- 1/4 red bell pepper, chopped
- 1 serrano chile pepper, minced
- 1 habanero pepper, minced (wear gloves)
- 1 carrot, minced
- 1 teaspoon butter
- 1/2 cup chopped fresh mushrooms
- 1/4 cup bread crumbs
- 1/2 cup grated Parmesan cheese
- 1 cup arugula, or to taste
- Spray a skillet with cooking spray and place over medium heat; cook chicken in the hot skillet until no longer pink in the center and the juices run clear, 6 to 8 minutes per side. Set chicken aside.
- Preheat oven to 350 degrees F (175 degrees C). Spray a 9×13-inch casserole dish with cooking spray.
- Place broccoli in the prepared casserole dish.
- Melt 3 tablespoons butter in a saucepan over medium heat; stir flour into the melted butter until combined and thickened, 3 to 5 minutes. Slowly pour in chicken stock and milk, stirring constantly; continue cooking and stirring until sauce is thickened, 5 to 10 more minutes.
- Stir onion, red bell pepper, serrano chile pepper, habanero pepper, and carrot into the sauce; simmer until vegetables are slightly softened, 5 to 10 minutes.
- Cut the cooled chicken into cubes and sprinkle over broccoli. Pour sauce over chicken and broccoli.
- Heat 1 teaspoon butter in a skillet over medium heat; cook and stir mushrooms until tender, 5 to 10 minutes. Spoon over sauce layer in the casserole dish. Sprinkle bread crumbs and Parmesan cheese over mushroom layer.
- Bake in the preheated oven until cooked through and bubbling, about 30 minutes. Turn on the oven's broiler; broil casserole until topping is browned, 2 to 4 minutes.
- Spoon casserole into 4 bowls and sprinkle 1/4 cup arugula atop each serving.