- Mix together the mash, ham and chives and season with salt. Roll into balls and flatten, place a cube of gruyere in the middle and roll back into a ball, with the cheese in the middle.
- Heat the oil to around 170°C/340°F.
- Roll the balls in the flour first, then the egg, and finally the panko breadcrumbs.
- Fry in batches for around 3 minute, until they've turned a golden brown colour.
- Serve warm with ketchup and mayonnaise.