In the over, bake the potatoes at 400 degrees F for one hour, then peel and mash coarsely.
In a large casserole, cook the bacon and onions over medium heat until onions are translucent.
Sprinkle the flour over the onions and bacon and stir until the mixture starts to bubble.
Lower the heat and gradually whisk in the milk until blended. Turn heat back to medium and allow the milk mixture to thicken and come to a slow boil while stirring.
Add mashed potatoes and cheese stirring until the cheese is melted.
Lower the heat and add the crème fraiche, black pepper, and half of the scallions. Cook over low heat for about 10 minutes, until hot. (do not boil).
Place soups in 8 bowls and garnish with remaining scallions and more grated cheese if you’d like.