Scrub potatoes, pat dry. Prick potatoes w/ a fork. Bake at 425 for 1 hr. Cool completely. Cut potatoes into cubes. In lg dutch oven, melt butter, over medium heat.
Add onion and celery. Cook, stirring for 5 mins. Stir in flour, thyme, salt and pepper. Stir in light cream. Cook, stirring, until thickened.
Add potatoes, 1 cup cheese and broth. Stir until cheese melts. Mash potatoes w/ a masher. Reserve 2 tbsp bacon. Stir remaining bacon and 1 tbsp green onion into soup. Top each serving w/ reserved bacon, remaining chees, green onion and a dollop of sour cream.