Heat the stock to a simmer and add the porcini mushrooms. Turn off the heat and leave to soak while you prep the rest of your ingredients.
When the mushrooms have been soaking for at least 10 minutes scoop them out of the stock and chop then get the stock back up to a low simmer.
Add the olive oil and butter to a large pot then add the onion and cook for a couple of minutes before adding the rice. Stir the rice for a few minutes to toast it then add a ladleful of stock and cook until all the liquid has been absorbed.
Keep adding stock a ladleful at a time, stirring continuously and making sure most of the liquid has been absorbed before adding more. When you've used half the stock add the black garlic, porcini mushrooms and chopped mushrooms. Continue to add stock in the same way until the rice is cooked and the consistency is to your liking.
Add the parmesan and goat's cheese and combine. Serve topped with extra goat's cheese and parsley.