Pierce potatoes with a fork. Microwave on HIGH 13 minutes or until tender. Cut in half; cool slightly.
While potatoes cook, heat oil in a saucepan over medium-high heat. Add onion; saute 3 minutes. Add broth. Combine flour, and ½c. milk; add to pan with 1½c. milk. Bring to a boil; stir often. Cook 1 minute. Remove from heat; stir in sour cream, salt, and pepper.
Arrange bacon on a paper towel on a microwave-safe plate. Cover with a paper towel; microwave on HIGH for 5 minutes. Crumble bacon.
Discard potato skins. Coarsely mash potatoes into soup. Top with cheese, scallions, and bacon.
Recipe by The Gingham Apron at https://www.theginghamapron.com/loaded-potato-soup/