Preheat the oven to 400°F

Line a baking sheet with parchment paper and add the Panko bread crumbs, distribute them evenly and bake them on the middle rack for 10-15 minutes until lightly browned. Allow them to cool.

Place the cold smashed potatoes in a bowl and use a masher or fork to break it up and make it as smooth as possible.

Add one egg (reserve the other egg for the coating). Add the bacon, cheese, ½ cup of the chives, salt, and pepper. Add 2 tablespoons of sour cream and reserve the rest for serving. Stir the potato mixture thoroughly to combine all the ingredients.

Add the second egg to a dish and lightly whip it with a fork. In a second dish add the toasted bread crumbs.

Using a medium-size cookie scoop, form balls with the potato mixture, dip each potato ball into the egg mixture and then roll it into the toasted bread crumbs and place onto the prepared baking sheet.

Transfer the baking sheet to the middle rack of the oven and bake for 20 minutes. Remove from the oven and transfer the crispy mashed potato balls to a serving dish. Serve warm with sour cream and the reserved ¼ cup of chopped chives