Spread the butter substitute of each slice of bread.
Divide the Parmesan between each slice, on the buttered side. Spread evenly and press it down lightly.
Preheat the pan on medium heat and spay with a little bit of Pam.
In a small bowl, mix the spinach, feta, green onion, salt and pepper until all combined.
Place one slice of bread in the pan, Parmesan side down. Top off with the spinach/feta mixture(evenly and press it lightly).
Cover with the second slice of bread, Parmesan side up. Press it down and cook on medium-low heat, covered, for about 5 minutes on each side. (Be careful flipping it, and press it again after you flip it.)