Season the chicken pieces on both sides with salt, pepper, and half of the Italian seasoning.
Heat the olive oil in a large skillet over medium-high heat. Sear the chicken for 4-5 minutes per side, until golden and cooked through (165°F internal). Transfer to a plate.
Lower the heat to medium and add the butter and garlic. Cook for about 30 seconds, until fragrant.
Pour in the chicken broth and heavy cream, scraping up any browned bits. Stir in the parmesan and remaining Italian seasoning and simmer for 2-3 minutes until slightly thickened.
Add the sun-dried tomatoes and spinach, and cook until the spinach wilts, about 2 minutes.
Return the chicken to the skillet, spoon the sauce over the top, and simmer for another 2 minutes before serving.