01 - Preheat oven to 400°F. Lightly grease a baking sheet or line with parchment paper.
02 - If not using leftovers, peel and boil potatoes until tender. Drain thoroughly and mash with butter, milk, salt, and pepper until smooth. Allow mixture to cool slightly.
03 - In a large mixing bowl, combine mashed potatoes, shredded cheddar, grated Parmesan, eggs, chopped chives, smoked paprika, and flour. Mix until fully incorporated and smooth.
04 - Using a spoon or small ice cream scoop, portion mixture into 12 evenly sized dollops on the prepared baking sheet, spacing them apart.
05 - Brush the tops of each puff lightly with melted butter to promote golden browning.
06 - Bake for 25 to 30 minutes until puffs are golden brown and set throughout.
07 - Allow puffs to cool for several minutes on the baking sheet. Serve warm, optionally accompanied by sour cream.