Scrub baking potatoes with a brush. Prick with a fork in several places. Place potatoes in a shallow baking dish. Micro-cook, uncovered, on 100% power for 6 to 8 minutes or till potatoes are tender. Cut a lengthwise slice from the top of each potato. Discard the skin from the lengthwise slices, place the potato portions from the lengthwise slices in a mixing bowl. Scoop out the insides of the potatoes leaving two 1 cm thick shells; reserve the shells. Add the insides of the potatoes to the mixing bowl containing the potato portions from the top slices; mash. Stir in shredded cheddar cheese, butter or margarine and sliced green onion. Beat in enough milk to give the mixture a stiff consistency. Season to taste with salt and freshly ground pepper. Pile the mashed potato mixture into the reserved potato shells. Return to the shallow baking dish. Micro-cook, uncovered, on 100% power for 2 to 3 minutes or till potato mixture is heated through. Sprinkle with paprika, if desired.