Preheat oven to 375°F.
Lightly grease a 12-cup muffin pan with olive oil spray or butter.
In a large mixing bowl, combine the mashed potatoes, shredded cheese, beaten eggs, sour cream, flour, Parmesan cheese, chopped chives, and salt. Stir until well blended.
Spoon the mixture evenly into the prepared muffin cups, filling each about three-quarters full.
Bake for 35–40 minutes, or until the tops are golden brown and the cheese puffs are set.
Let the cheese puffs cool in the pan for 5 minutes, then carefully remove them with a soft-sided spatula by loosening the puffs from the edges of the muffin pan.
Serve warm on their own or with sour cream.