Risotto

1 large onion

1 lb. (1/2 kg) mushroom
2 oz. (50 g) butter
4 oz. (100g) Patna rice
1 chicken stock cube
1 pint (500 ml) boiling water
salt and pepper
pinch of saffron powder
4 tablespoon olive oil
parsley
2 oz. (50 g) grated Parmesan cheese