Preheat oven to 400 degrees F. Rub potato skins with oil, sprinkle with salt and pepper and rub potatoes to coat. Bake potatoes in preheated oven 50-60 minutes, or until soft. Do not wrap potatoes in foil. Remove potatoes from oven and slice skin off the tops. Scoop potato flesh into a large bowl, reserving intact skins. To potatoes, add all but two tablespoons of cheese plus egg, butter, roasted garlic and liquid smoke if using. Mash potatoes while gradually adding milk. Spoon mixture into skins and top with remaining cheese. Bake for an additional 15 minutes or until golden brown.