- Preheat your oven to 350°F (175°C) and grease a 9-by-13-inch baking dish with some butter. 
- Season the chicken cutlets with salt and pepper, then melt 1 tablespoon of butter in a skillet over medium heat. 
- Cook the cutlets for about 2-3 minutes on each side until they're nicely browned. 
- Arrange the browned chicken cutlets in the baking dish. 
- Layer each cutlet with a slice of ham and Swiss cheese. 
- In a bowl, mix the cream of chicken soup, milk, and mustard. 
- Pour this creamy mixture evenly over the chicken cutlets. 
- Combine the breadcrumbs and grated Parmesan cheese in a small bowl, then sprinkle over the top of the casserole. 
- Bake for 25-30 minutes until bubbly and golden on top.