Prawn risotto for four people

In a casserole dish melt two knobs of butter in a spoon of extra virgin olive oil. Sauté a finely chopped small onion, add 300g of Carnaroli Grandi Riso rice and toast slightly, add ½ a cup of white wine, leave to evaporate and gradually add boiling stock (slightly salted) until the rice is cooked.
Add 200g of shelled and washed prawns five minutes before the end of cooking.
Take the risotto off the flame, stir in two knobs of butter, three desert spoons of Parmesan cheese and a handful of chopped parsley.