Preheat the oven to 375°F (190°C). Lightly grease a 9x13 inch baking dish.
In a mixing bowl, combine mayonnaise (or sour cream), Parmesan cheese, garlic powder, onion powder, paprika, salt, and pepper.
Place the chicken breasts in the baking dish and spread the creamy mixture evenly over the top of each piece.
Bake for 25–30 minutes, or until the internal temperature of the chicken reaches 165°F (74°C) and the top is golden and bubbly.
Rest the chicken for 5 minutes before serving. Garnish with chopped parsley if desired.