Make 4 crosswise incisions in the onions; do not cut all the way through.
Place the onions with the root facing downwards on a baking tray lined with baking paper, drizzle with oil, season with salt. Place the sprigs of thyme in the incisions.
Approx. 1 hr. in the centre of an oven preheated to 180°C.
Heat the oil in a pan. Add the rice and sauté until translucent, stirring continuously. Pour in the wine and reduce completely. Gradually add the hot stock, stirring frequently, so that the rice is always just covered with liquid, simmer for approx. 20 mins. until the rice is creamy and al dente. Mix the cheese and butter into the risotto.
Nut and salami topping
Coarsely chop the nuts, dice the salami and pear. Remove the thyme leaves from the stalks.
Dry-roast the nuts in a non-stick frying pan for approx. 3 mins. Add the salami, pear and thyme, stir fry for approx. 7 mins., season. Plate up the risotto, arrange the onions on top, gently open up, sprinkle with the nut and salami topping.