Bring the stock to the boil in a saucepan, or bring the water to the boil and stir in the stock powder. Add the wine, reduce the heat and leave to simmer.
Rinse the spinach leaves, chop roughly and put aside.
Heat the oil in a large saucepan or wok. Peel and finely chop the onion and garlic and fry gently for 2–3 minutes, until soft but not brown. Then add the rice and stir-fry until the grains are translucent and coated with oil.
Add a ladleful of stock, adjust the heat to maintain a gentle boil, and stir until most of the liquid has been absorbed. Keep adding stock, a ladleful at a time, and stir constantly for about 15 minutes, until the rice is almost cooked.
Add the spinach and more stock and stir until the rice is cooked – risotto rice should retain a bite, but the mixture should be of a soft, dropping consistency.
Season to taste with salt, pepper and grated nutmeg. Serve straight from the pan.