Fire your oven, and let the temperature fall to about 400-450ºF.
On cook top, heat the olive oil and add the onion and a pinch of salt. Cook until the onion is soft and translucent. Add the rice, stirring to coat with the oil. This can also be done in the oven. Add the stock, wine, chard leaves and stems, asparagus, nutmeg, teaspoon of salt and bring to a simmer. Stir in half of the cheese.
Transfer to a buttered heat-resistant terracotta casserole and smooth out the top. Sprinkle with the rest of the cheese and cover with foil.
Place the baking dish on the floor of the oven near the center. Bake until the rice is cooked through and has absorbed most of the liquid, 20-30 minutes or so. The rice should be moist but not soupy. Remove the foil cover for the last 10 minutes of baking to create a beautiful golden crust and to add smoky flavor.
Serve immediately.