Preheat the oven to 425 degrees Farenheit. Clean the baked ptoatoes, poke with a fork and bake on a tray for 45 minutes.
While potatoes bake, cut the bacon strips in 1/2 inch pieces. Fry in a cast iron skillet until golden brown and crispy. Remove the bacon from the pan. Add in the diced onion and celery and cook until translucent about 10 minutes on medium heat, stirring constantly.
Once the potatoes are done, carefully, remove the baked potatoes from the oven, cut in half and scoop out the flesh. Potatoes might still be a little hard--it's okay. You'll want to chop into cubes. Add to the stock pot. Mix in 1/4 cup sour cream. Blend well and season with salt and pepper.
Then, mix the chicken stock with the all-purpose flour until well blended. Pour the mixture into the stock pot and add in the milk. Increase heat to medium-high for 5 minutes until simmering.
Add in 3/4 of the chopped green onions, parsley, half of the cooked bacon, and the shredded cheddar cheese. Mix well and begin to ladle soup in bowls. Top each bowl of soup with additional sour cream, green onions, shredded cheddar cheese, and bacon pieces.