In a medium bowl, combine the melted butter, milk, eggs, and mashed potatoes. Gently stir to combine.
In a small bowl, combine the flour, baking powder, baking soda, salt, and pepper. Add into the mashed potato mixture, stirring until just combined.
Heat and grease a waffle iron. Cook waffles (about a heaping ⅓ cup of batter at a time) until golden on both sides. Preheat oven broiler. Place cooked waffles on a cookie sheet. Top with cheese. Broil until cheese is melted, about 1 minute.
Mix together sour cream and smoked paprika. Serve waffles topped with sour cream mixture, bacon, and chopped chives.