1Microwave potatoes as directed on package.
2In large microwavable bowl, mix hot potatoes and 2 cups of the milk; mash until smooth. Add 3/4 cup of the cheese and stir until melted. Stir in remaining 1/2 cup milk, the sour cream and salt. Cover; microwave on High 2 to 3 minutes or until thoroughly heated.
3Ladle soup into 6 bowls; sprinkle evenly with remaining 1/4 cup cheese and the onions. Garnish with pepper and bacon.