In a large bowl, whisk together the egg, apple, mustard, maple, liquid smoke, salt, paprika and pepper. Add the ground pork and mix with your hands. Add the Panko bread crumbs and keep kneading until well mixed.
Form the meat into four burgers.
Heat a large non-stick skillet over medium heat. Add the burgers and cook until starting to brown, about 5 minutes. Flip and cook until starting to brown on the second side. Add the hard cider to the pan and cook until all the cider has evaporated.
Check the burgers with a meat thermometer to make sure they've reached temperature (160 degrees). If not keep cooking a little longer.
Serve each burger on a toasted bun with a slice of applewood smoked bacon, mayonnaise, fresh spinach, melted Havarti cheese, pickled onions and apple butter.