Lightly sauté the mushrooms in a non-stick frying pan (you may need a little oil to do this).
Add rice and toss to coat; cook for 1-2 minutes or until lightly toasted.
Pour 1 cup (250ml) stock into the rice. Stir until absorbed.
Gradually add the stock in batches, stirring regularly, cooking for 20 minutes or until rice is al dente.
Remove from heat and stand for 2 minutes. Add three-quarters of the Parmesan and season to taste.
When ready to serve, spoon across four bowls and sprinkle with remaining Parmesan.