In a medium sized skillet melt butter over medium heat. Add garlic and sauté for one minute. Season chicken with salt and add to the skillet. Sauté chicken pieces for 3 to 5 minutes or until no longer pink, coating the chicken with the garlic butter as it cooks. Add the spinach in the last minute and cook until wilted. Finishing with the parmesan cheese and stir to coat the chicken.