Preheat your oven to 400°F (200°C) and lightly grease a 9x13-inch casserole dish.
Place each chicken breast between two sheets of plastic wrap. Using a rolling pin or the flat side of a meat mallet, gently pound each piece to a uniform thickness of about 0.5 to 0.75 inches. Rub olive oil thoroughly over the chicken.
In a small bowl, mix together the brown sugar, garlic powder, onion powder, paprika, Italian seasoning, salt, and black pepper. Evenly sprinkle the seasoning blend over the chicken, then gently rub it in.
Arrange the seasoned chicken breasts in the prepared dish, placing a small piece of butter on top of each. Bake for 18-20 minutes, or until the internal temperature of the chicken reaches 165°F. For a nicely browned finish, broil the chicken for an additional 1-3 minutes if desired. Serve immediately.