1.Combine stock and the water in large saucepan, bring to a boil then reduce heat to simmer gently.
2.Meanwhile, heat half of the butter and half of the oil in another large saucepan, add mushroom, cook, stirring, until browned lightly. Add garlic, cook, stirring, until fragrant. Remove from pan, cover to keep warm.
3.Heat remaining butter and remaining oil in same pan, cook onion, stirring, until soft. Add rice, stir over medium heat until rice is coated in butter mixture. Stir in 1/2 cup (125ml) of the stock mixture, cook, stirring, over low heat until liquid is absorbed.
4.Continue adding stock mixture, in 1/2-cup batches, stirring after each addition until liquid is absorbed. The total cooking time should be about 20 minutes or until rice is tender.
5.Stir in mushroom mixture, parsley, cheese, extra butter and rocket. Top with extra parmesan cheese flakes, if desired.
This recipe is best made close to serving.Note