1. Grate and squeeze the potatoes.
2. Place the potatoes in a bowl, add the eggs, flour, salt, rosemary, and oil, and mix well.
3. Grease a non-stick frying pan with a little olive oil, and cover the bottom with half of the potato mixture.
4. Top with slices of ham and cheese and top with the remaining potato mixture.
5. Cook over medium-low heat for 10 minutes on each side.
6. Serve immediately.
