Pierce potatoes with a fork. Microwave on high for 13 minutes or until potatoes are tender. Cut potatoes in half; cool slightly, then coarsely chop and set aside. In a large saucepan sauté onion in olive oil until translucent, about 3 minutes. Add chicken broth to pan. Combine flour and ½ cup milk in a small bowl, stirring until smooth; add flour mixture to pan with remaining 1½ cups milk. Bring soup to a bowl stirring frequently. Cook 1 minute. Stir in potatoes and cook for an additional 5 minutes. Using a hand blender puree the soup slightly. You still want it to be a little chunky. Remove soup from heat; stir in sour cream, butter, salt, and pepper. You might need to add a little more chicken stock to thin out. Ladle into bowls and serve with 1 slice crumbled bacon, 2 tablespoons shredded cheese, and green onions.