Remove any fat from the ham. Cut the ham into thin slices and leave to one side. Finely chop the onion. Heat the oil and butter in a large saucepan over a gentle heat and cook the onion for 5 minutes, until soft and golden.

Mix the rice with the onion and continue cooking it over a moderate heat for 5-7 minutes, until the grains of rice begin to burst. Meanwhile, heat the stock.

Stir the wine into the rice until it has been absorbed. Add 1/4 pint (150 ml) of the hot stock. Mix well and cook over a moderate heat until the stock has been absorbed, stirring continuously.

Continue cooking for 20 minutes, adding the remaining stock in 1/4 pint quantities, until the rice is tender yet firm and the texture is creamy. Add the peas with the last measure of stock and season to taste.

Fold in the ham and 1 oz (25 g) of the Parmesan. Divide the mixture between serving bowls, sprinkle with the remaining Parmesan and serve.