01 - Generously season both sides of each chicken breast with salt, black pepper, and Italian seasoning, pressing the spices into the meat to ensure even coating.
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 to keep warm.
03 - Reduce heat to medium. Add chopped onion and minced garlic to the same skillet, sautéing for 2–3 minutes until fragrant and translucent, being careful not to burn the garlic.
04 - Pour in chicken broth, using a wooden spoon to scrape up any browned bits from the bottom of the skillet. Allow the liquid to simmer and reduce for 2 minutes, concentrating the flavors.
05 - Stir in heavy cream and grated Parmesan cheese, whisking continuously until the cheese melts and the sauce becomes smooth and velvety. Simmer gently for 2–3 minutes until slightly thickened and coating the back of a spoon.
06 - Return the chicken breasts to the skillet, spooning sauce over each piece. Simmer for 3–5 minutes until the chicken is heated through and flavors have melded. Garnish with fresh chopped parsley and additional Parmesan cheese. Serve immediately.