1. Place potato in a large saucepan; cover with cold water. Bring to a boil. Reduce heat; simmer 15 minutes or until tender. Drain well; return potato to pan over medium-low heat. Add milk; mash potato mixture with a potato masher to desired consistency. Cook 2 minutes or until thoroughly heated, stirring constantly. Remove from heat. Add cheese, and stir until cheese melts. Stir in sour cream, pepper, and salt. Top with green onions and bacon.