Heat oil in a pan and add the onion, cooking until soft. Add the mushrooms, garlic and kale and cook for 2-3 minutes until soft. Add the rice and cook for 1 minute, then season the mixture. Go easy on the salt if using parmesan as this is salty.
Add 300 ml of the stock to the pan, and cook, stirring until absorbed. Add the rest of the stock in two more batches, stirring until absorbed and the rice has the desired bite and consistency. Stir in the nuts and creme fraiche. Serve, with parmesan shaved over the top if desired.