Cut the peeled potatoes into quarters and put them into a pot. Cover them with 1 inch of water then bring the pot to a boil.
Boil until the potatoes are soft, about 12-15 minutes. Drain the water, then put the potatoes back into the pot.
Add the butter and salt to the potatoes and mash them well with a potato masher. Put them into the fridge, uncovered, and let cool.
When the potatoes are cold, add the bacon, cheddar cheese, chives, and 1 egg to the mashed potatoes and mix well.
In a wide bowl, whisk the remaining 2 eggs with 2 tablespoons of water. Add the panko to another wide bowl.
Use a medium-sized cookie scoop to scoop out 28 balls. Dip the balls first into the egg and then into the panko. Move all the rolled balls to a cookie sheet or a plate.
Heat the oil in a high-sided frying pan. Working in 2-3 batches, fry the mashed potato balls just until they turn golden.
Notes
This is a great recipe to use leftover mashed potatoes, like these Roasted Garlic Mashed Potatoes. You'll need about 3 cups of leftover mashed potatoes to make this recipe.