Peel and dice the potatoes, then add them to a pot of cold water with 1 tsp salt. Bring to a boil and cook until the potatoes and just about fork-tender. It's important that you don't over-boil the potatoes, otherwise they'll soak in too much water and the balls will be too sloppy to mould.
Drain the potatoes in a colander and leave them to steam dry and completely cool. It's important to let the steam escape from the potatoes so they can dry out. To speed up this process, you can lay them on a towel until they're completely cool.
Mash the potatoes with the butter, cheddar, bacon, chives, salt and pepper. Use a 1 tbsp measuring spoon to scoop out the mixture into portions. Take a piece of cubed cheese and use a portion of mash to wrap into a ball. You should get 14-15 balls in total.
At this point I highly recommend placing them in the freezer for 15 minutes to firm them up before coating them.
In a small bowl, combine 1 tsp smoked paprika, 3/4 tsp salt and 1/4 tsp garlic powder, black pepper and cayenne pepper. Line up 3 large shallow dishes: the first with the flour and half of the seasoning mixed in, the second with the beaten eggs and the third with the Panko and the rest of the seasoning.
Coat the mashed potato balls in the flour, then the egg, then the Panko, ensuring they're fully coated at each stage (namely the Panko). You can do this a few at a time, depending on the size of your dishes.
In a pot suitable for frying, add enough oil to cover the height of the balls and heat to 180C/350F (a breadcrumb should rapidly sizzle). Use a slotted spoon to lower the balls into the oil (I do 4 or so at a time) and fry them for 2-3 minutes, or until golden and crisp. Use your slotted spoon to gently and continually move them around so they fry evenly. You might spot little dots of leakage, which is fine, but if one of them looks like it's about to split open, just remove it. Place the cooked balls on a wire rack above paper towels to catch excess oil.
Finish with parmesan and parsley then tuck in and enjoy!