Bring around 600ml of water to a boil in a kettle or saucepan.
In the meantime, chop the shallots finely.
Heat the olive oil in a large saucepan over medium heat and add the shallots. Sauce the onions in the olive oil for around 2-3 minutes stirring throughout. Be careful not to brown them.
Add the rice and stir well coating all rice-grains in the oil, approx. 2-3 minutes
Pour in the prosecco and glaze the rice. The turn up the heat and bring to a gentle boil. Let it cook down, stirring often.
Now add the vegetable stock and 1/2 tsp of salt. Continue cooking until the liquid reduces again. Remember to stir often and scrap the bottom to not let any rice stick.
Continue adding water until the rice is nearly cooked.
When the water has almost completely been absorbed and the rice is cooked, turn off the heat and add the butter and half the grated cheese. Add the truffle oil, if using. Stir thoroughly until the butter and cheese are melted and the risotto is creamy.
serve the risotto on individual plates or bowl and, using a potato or vegetable slicer, shave 2 or 3 thin pear shavings on top. Sprinkle with thyme or a little parsley and finish by shaving very fine slices of white truffle over each portion. (5-8gr per portion).
Serve immediately.