Bake for 20–25 minutes, turning once halfway through, until the potatoes are tender and lightly golden. Remove the pan from the oven and sprinkle the shredded cheese evenly over the potato rounds. Return to the oven and bake for another 5–8 minutes, or until the cheese is melted. Finish with scallions and bacon, if using, and serve warm with a dollop of sour cream.