Scrub the potatoes and pierce in several places with a small knife. Bake in a preheated 350-degree oven about 1 1/4 hours, or until tender. Cool slightly: cut a thin slice from the tops of the potatoes and coop out the insides, leaving a thin shell. Place on baking sheet. Mash the potato pulp with a fork. Combine the margarine and garlic; brush lightly over the insides of the potato shells. Add the remaining to the pulp. Mash in the cream cheese. Add the Parmesan, sour cream, parsley, chives, salt and pepper. Fill the potato shells and bake in a preheated 350-degree oven 15-20 minutes, until heated through. Finish under the broiler, cooking until golden.