Bring 1 litre of water to the boil, add the stock cubes and stir until dissolved.
Peel and finely chop the onion.
Heat the oil in a large frying pan and gently fry the onion for 3-5 minutes. Add the rice and heat over a medium fire until translucent. Add the wine and continue to stir until it has been absorbed by the rice.
Add the stock, one ladle at a time, continually stirring and waiting until the stock has been fully absorbed before adding any more.
Add the remaining stock in this manner until the rice has been cooked 'al dente' (about 20 minutes). When done, the risotto should be creamy but not mushy.
While the risotto is cooking, peel the pears, remove the cores and cut into cubes. Sprinkle the pears with lemon juice to prevent discolouration.
Heat the butter in a frying pan and briefly sauté the pears.
Add the hot pears and Parmesan cheese to the risotto and season with salt and pepper.