Preheat oven to 375°F, grease a 9×13 baking dish, flatten thick chicken breasts to about 1 inch, pat dry, and season with salt and pepper.
Optional: Heat olive oil in a skillet and sear chicken 2–3 minutes per side until lightly golden.
Mix sour cream, mayonnaise, garlic powder, onion powder, smoked paprika, salt, pepper, and grated Parmesan until smooth and creamy.
Place chicken in the baking dish and spread the creamy mixture evenly over each piece; add extra shredded cheese if desired.
Bake 35–40 minutes until chicken reaches 165°F and the top becomes lightly golden and bubbly.
Rest 5 minutes, then garnish with parsley or chives and serve.