In a large pot over medium-heat, add the quartered potatoes and chicken broth. Cook until the potatoes are fork-tender, about 20-25 minutes. Remove from heat.
While you're waiting for the potatoes to cook, add the bacon slabs to a medium-sized pan and cook the bacon until crispy, about 6 minutes on each side. Set aside on a paper towel-lined plate to cool, then crumble into small pieces.
Once the potatoes are fully cooked, purée the potato-broth mixture with an immersion blender until smooth or transfer to a food processer in batches and blend until liquified, returning to the pot when finished. Add in the milk and cheese and mix until fully incorporated. Season with salt and pepper, to taste.
To serve, garnish with a dollop of sour cream, a sprinkle of shredded cheese and crumbled bacon, and a little of the sliced parsley or scallions.