Preheat oven to 375° Fahrenheit. Lightly grease baking dish with cooking spray and set aside. Trim chicken breasts; if chicken breasts are very thick, slice them in half to create thinner cutlets.
Lightly season all sides of chicken with salt and pepper to taste. Place chicken breasts in greased baking dish, being careful not to stack or overlap if possible.
In small bowl, whisk together sour cream, mayonnaise, and shredded parmesan until mixture is well combined. Pour mixture over chicken breasts and spread evenly.
In second small bowl, whisk together breadcrumbs and melted butter until ingredients are thoroughly combined. Crumble mixture evenly over tops of chicken breasts.
Place baking dish in preheated oven. Bake, uncovered, 30 minutes, or until chicken is fully cooked through. Remove baking dish from oven and serve chicken warm with preferred sides and fresh parsley garnish if desired.
If the chicken breasts are very thick, they'll take longer to cook and you'll risk them drying out. Slicing them in half (like a hamburger bun) will help them stay tender and moist.
Cook until chicken reaches an internal temperature of 165° Fahrenheit.
Make it Gluten Free: Use gluten-free breadcrumbs.
Make it Keto: Use crushed pork rinds mixed with Italian seasoning instead of using Italian breadcrumbs.