Boil the potatoes in salted water for 15 minutes until very tender. Drain well and mash until smooth. Let cool slightly.
Add the spring onions, herbs, half the cheese and a good pinch of salt and pepper to the mash. Mix well.
Shape the mixture into 8 flat cakes. Dip each cake in the beaten egg, then coat in flour.
Heat the oil in a large frying pan over medium heat. Fry the potato cakes for 4-5 minutes on each side until golden and crispy.
Place the remaining cheese on top of each cake during the last minute of cooking and let it melt.
Serve with a side salad or baked beans.