Season the chicken breasts with salt and black pepper on both sides.
In a large skillet, heat the olive oil over medium-high heat. Add the chicken breasts and cook for 4-5 minutes per side, or until they are golden brown and cooked through. Remove the chicken from the skillet and set it aside on a plate.
In the same skillet, add the chopped onion and sauté for 2-3 minutes until it becomes translucent.
Add the minced garlic to the skillet and sauté for another 30 seconds until fragrant.
Pour in the diced tomatoes (with their juice) and add the dried oregano, dried basil, dried thyme, and dried rosemary. Stir to combine.
Reduce the heat to low and return the cooked chicken breasts to the skillet. Cover them with the tomato mixture.
Pour in the heavy cream and sprinkle the grated Parmesan cheese over the top.
Cover the skillet and simmer for 10-15 minutes, allowing the flavors to meld and the sauce to thicken.
Check the seasoning and adjust the salt and pepper if needed.
Garnish with fresh basil leaves just before serving, if desired.
Serve the Creamy Italian Chicken hot over cooked pasta, rice, or with crusty bread to soak up the delicious sauce.