1) In a deep frying pan, fry the onions and garlic in the olive oil for a couple of minutes to soften.
2) Add the rice and stir to coat with the oil
3) Add a ladle full of the stock, turn the heat down to low and allow to cook until it has disappeared.
4) Continue to add the stock a ladle at a time until it is all used up and the rice is cooked to your liking. Add more water if necessary.
5) Add the prawns, peas, truffle oil and butter, and heat through.
6) Taste and check the seasoning, add the black pepper and salt if needed.
7) Scatter the parmesan over the top and serve.