Bake the potatoes at 425°F for 50 to 60 minutes until tender, cool slightly and scoop out the flesh.
Cook the bacon until crisp and at least 145°F, rest it for 3 minutes and crumble it.
Melt the butter in a Dutch oven and cook the onion for 6 minutes, then stir in the flour for 2 minutes.
Whisk in the broth and milk and simmer for 8 minutes.
Mash half the potato flesh into the broth, fold in the remaining chunks, sour cream, salt and black pepper, and warm to 165°F.
Serve with cheddar, bacon and scallions divided among the bowls.