- potatoes - 5 small or 3 large
- 2 leeks
- mustard (your preference, I use French or Dijon)
- 1 egg
- 1 block of gruyere, grated
- a small amount of parmasen cheese, grated
- shortcrust pastry (make your own, or if in a hurry, use frozen sheets)
Once the potatoes are cooked, run under some cold water to cool them quickly, then slice in half longways, then in half centimeter slices (half moon shaped).
Mix together the leeks, potatoes, raw egg and half the gruyere cheese with some salt and pepper. Be careful to mix carefully so the potatoes do not turn to mash.
Spread a generous layer of mustard over the floor of the pastry, then spoon over the potato and leek mixture and spread it to the edges. Cover with the remaining gruyere and the parmasen and bake for a further 15 or 20 minutes, until the top is browning.