Preheat your oven to 375°F.
In a mixing bowl, combine sour cream, mayonnaise, cheddar cheese, garlic powder, onion powder, paprika, salt, and black pepper. Mix until well combined.
Place the chicken breasts in a greased 9x13 inch baking dish. Spread the sour cream mixture evenly over the chicken.
Sprinkle the grated Parmesan cheese on top of the mixture.
If using, sprinkle chopped green onions over the top.
Bake in the preheated oven for 30-35 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F.
Remove from the oven and let it rest for 5 minutes before serving.