Crumble the stock cube into the boiling water and stir until dissolved. Chop the fresh mushrooms into small pieces, and slice a couple of them vertically for form.
Heat the oil in a saucepan or deep frying pan over a moderate heat. Add the onions and garlic, and fry for 5 minutes until soft. Stir in the fresh mushrooms, season with salt and pepper and continue to cook for 6-8 minutes until the mushrooms are tender and soft.
Add the rice into the pan and cook for 1 minute coating it in the juices and oil. Pour over the wine and let it simmer and reduce. Over a medium heat, pour in a quarter of the vegetable stock. Simmer the rice stirring often to avoid sticking until the rice has absorbed all the liquid.
Add the same amount of stock again and continue to simmer and stir until the stock is absorbed. Repeat.
Add the final quarter of stock and stir until absorbed. The rice should be soft and tender. Take care not to let the rice stick. If the rice is still undercooked add a little boiling water and simmer for a few more minutes.
Add the butter and give it a good stir. Sprinkle Parmesan cheese and fresh parsley before serving.