Heat the oil in a pan, add the rice and cook, stirring, until glassy.
Add a ladleful of stock and the white wine. Allow the liquid to boil away, stirring occasionally.
Meanwhile, clean and finely chop the mushrooms.
Add the mushrooms to the rice.
Mix well. Again, add some stock and allow to boil, stirring over a medium heat until almost completely absorbed. Continue adding stock and cooking in this way until the rice is tender with a little bite - about 15-20 minutes.
Wash the spinach and shake dry.
Add to the risotto, cover and allow to wilt over a low heat for 1-2 minutes.
Stir the butter and parmesan into the risotto. Season with salt, pepper and nutmeg, and serve.