Peel the potatoes and slice them into pieces about 7 mm thick. Arrange them on a baking tray and dress with oil, salt and pepper. Bake in the oven at 180°C for about 15 minutes.
Remove from the oven and stack with the fontina or another sort of strong cheese cut into thin slices, and the cooked ham.
Place back in the oven for a few minutes, until the cheese is just melted.