Best Chicken Cordon Bleu Casserole Recipe - How To Make Chicken Casserole

Ingredients

• Cooking spray
• 3 oz. prosciutto
• 6 tbsp. unsalted butter
• 6 tbsp. all-purpose flour
• 1 c. chicken broth
• 1 c. whole milk
• 1 tbsp. Dijon mustard
• 1 1/2 tsp. kosher salt
• 1 tsp. freshly ground black pepper
• 2 lb. boneless, skinless chicken breasts, cut into 1" pieces
• 8 oz. cubed ham
• 4 c. shredded Swiss cheese (about 1 lb.), divided
• 1 c. panko bread crumbs
• Chopped fresh parsley, for serving