In a small bowl, stir together all the dried herbs and seasoning from the "For the Chicken" section.
Add the chicken breasts to a large ziplock bag. Add the seasoning mix to the bag. Shake well to coat the chicken evenly in the dried herbs mix.
Heat the oil in a skillet over medium-low heat. Add unsalted butter.
Add the chicken to the skillet and cook for about 5 minutes on each side. Move the chicken around from time to time to ensure it cooks evenly and it doesn't burn. Cover it for a minute with the lid, to help the chicken cook quicker, in this case reduce the heat to low.
Check if the chicken is no longer pink in the center, it can be just slightly uncooked as it will continue cooking in the sauce, but be careful, the center should not be pink. Remove from pan, place on a plate and cover tightly with foil.
Add the garlic to the pan and cook for 30 seconds, stirring continuously.
Stir in the sun-dried tomatoes and spinach, until the spinach is wilted.
Add the heavy cream, salt, and pepper to taste, and bring to a boil.
Add the Parmesan cheese, stirring until the sauce has thickened slightly.
Place the chicken back into the pan, spooning the sauce on top of the chicken. Its best to pierce the chicken with a knife a few times, it will absorb the sauce better. Cover and cook on low for about 5 minutes.