Season the chicken all over with salt and pepper.
Heat the oil in a skillet over medium-low heat.
Place the chicken in the skillet and cook until browned and the internal temperature reaches 160 degrees.
Remove the chicken from pan.
Add the garlic and onion, stirring until onions are translucent. Stir in the tomatoes and spinach until the spinach is wilted.
Add the heavy cream, salt, and pepper and bring it to a boil.
Add the Parmesan cheese and parsley, stirring until the sauce has thickened slightly.
Place the chicken back in the pan, spooning the sauce on top of the chicken.
Serve with pasta and enjoy!