Creating Cheesy Sour Cream Chicken is as simple as following these easy steps:

1. Preheat Oven: Begin by preheating your oven to 375°F (190°C).
2. Prepare Chicken: Place the boneless chicken breasts in a baking dish. Season with salt and pepper.
3. Mix Sauce Ingredients: In a mixing bowl, combine the sour cream, ranch dressing mix, garlic powder, and onion powder.
4. Spread Sauce: Evenly spread the sour cream mixture over the chicken breasts.
5. Add Cheese: Sprinkle the shredded cheddar and grated Parmesan on top of the sauced chicken.
6. Cover and Bake: Cover the baking dish with aluminum foil and bake for 25 minutes.
7. Uncover and Brown: Remove the foil and bake for an additional 10-15 minutes to allow the cheese to brown slightly.
8. Check Doneness: Ensure the chicken is cooked through (internal temperature of 165°F or 74°C).
9. Garnish and Serve: Remove from the oven and garnish with fresh parsley if desired.

These steps will lead you to an extraordinary dish that captures the essence of cheesy comfort food!