Heat oven to 350ºF. Coat 6- or 8-cup nonstick muffin pan with cooking spray.
In bowl, mix bacon, mashed potatoes and 1 cup cheese. Divide batter among muffin cups, filling each two-thirds full. Sprinkle evenly with remaining 1 cup cheese.
Bake potato puffs until tops are golden brown and cheese is melted.