Chicken and Broccoli Casserole

INGREDIENTS

• 3 quarts water
• 1 (12-ounce) package broccoli florets
• 4 (6-ounce) skinless, boneless chicken breast halves
• 1 (12-ounce) can evaporated fat-free milk
• 1/4 cup all-purpose flour (about 1 ounce)
• 1/4 teaspoon salt
• 1/4 teaspoon freshly ground black pepper
• Dash of nutmeg
• 1 cup fat-free mayonnaise
• 1/2 cup fat-free sour cream
• 1/4 cup dry sherry
• 1 teaspoon Worcestershire sauce
• 1 (10.75-ounce) can condensed 30% reduced-sodium 98% fat-free cream of mushroom soup, undiluted
• 1 cup (4 ounces) grated fresh Parmesan cheese, divided
• Cooking spray