1: Put the pasta on to boil.
2: Slice the shallots and leeks and fry them in olive oil and butter until softened, about 7-10 minutes.
3: Add the garlic and fry for another minute.
4: Meanwhile, mix the egg and Parmesan with a bit of pasta water.
5: Pour the drained pasta into the leek pan and remove from the heat.
6: Slowly dribble in the egg mixture, stirring constantly until you have a silky sauce.
7: Season and serve with more Parmesan.
