Bake potatoes 50 minutes, or until tender. Let cool. Cut each potato in half. With a spoon, scoop out pulp leaving 1/4-inch of potato in each half. Cut each half in half again to form quarters. Season with salt and pepper. Bake potato quarters for 15 minutes. (This will crisp them up so that they can be picked up easily.)
Mash 1 cup potato pulp with a potato masher (save remaining pulp for a later use). Stir in the sour cream, cheeses, tomatoes, green onions and parsley. Mixture will be sticky and hold together. With your hands, divide the mixture evenly between the potato skins, pressing the mixture into the skins. Sprinkle with fresh ground black pepper and bake for 15 minutes. Serve warm.