01 - Pat chicken breasts dry with paper towels. Season both sides generously with salt, black pepper, and Italian seasoning, pressing the spices into the meat to adhere.
02 - Heat olive oil and butter in a large skillet over medium-high heat until butter foams. Add chicken breasts and cook for 5–7 minutes per side until golden brown and internal temperature reaches 165°F. Transfer chicken to a plate and tent with foil.
03 - Reduce heat to medium. Add chopped onion and minced garlic to the same skillet. Sauté for 2–3 minutes, stirring frequently, until onion becomes translucent and garlic is fragrant but not browned.
04 - Pour in chicken broth, using a wooden spoon to scrape up any browned bits from the bottom of the skillet. Let the mixture simmer for 2 minutes to reduce slightly and concentrate flavors.
05 - Stir in heavy cream and grated Parmesan cheese. Whisk continuously until cheese melts completely and sauce becomes smooth and velvety. Simmer gently for 2–3 minutes until sauce coats the back of a spoon.
06 - Return chicken breasts to the skillet, turning to coat completely in the sauce. Simmer for 3–5 minutes until chicken is heated through and flavors meld. Sprinkle with fresh parsley and additional Parmesan before serving.