Bake potatoes at 375 degrees for 1 hour or until done. Cut in half and scoop out pulp into large mixing bowl. Add butter, milk, green onion, cheddar cheese, salt and pepper. Mash together with potato masher (will be slightly lumpy).
Pour mixture into a small baking dish (1 1.2qt). Top with cheddar cheese. Place in a 350 degree oven approximately 15 minutes until cheese has melted.