01 - Generously season both sides of each chicken breast with salt, black pepper, and Italian seasoning, pressing the spices into the meat to ensure adhesion.
02 - Heat olive oil and butter in a large skillet over medium-high heat until butter foams. Add chicken breasts and cook for 5 to 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 skillet; sauté for 2 to 3 minutes until fragrant, translucent, and just beginning to caramelize.
04 - Pour in chicken broth while scraping up browned bits from the bottom with a wooden spoon. Allow liquid to simmer for 2 minutes, reducing slightly to concentrate flavor.
05 - Stir in heavy cream and grated Parmesan cheese, whisking continuously until cheese melts completely and sauce becomes smooth. Simmer gently for 2 to 3 minutes until slightly thickened and coating the back of a spoon.
06 - Return chicken breasts to skillet, spooning sauce over each piece. Simmer for 3 to 5 minutes until chicken is heated through and flavors meld. Garnish with fresh parsley and additional Parmesan before serving.