Peel and finely dice the onions. Cut the pumpkin in half and scoop out the seeds. Use a knife to remove the skin and then cut into half centimetre cubes. Crush the chestnuts. Grate the parmesan.
Heat a saucepan and add a drizzle of olive oil. Add the onions and a pinch of salt and cook for 2 minutes. Add the diced pumpkin and cook for a few minutes, allowing the pumpkin to colour slightly. Add the rice to the pan, stir to coat in oil and cook until translucent. Deglaze the pan with the white wine and then cook until all of the liquid has evaporated. Add the vegetable stock to the pan one ladleful at a time, allowing each addition of liquid to be absorbed before adding more. Stir constantly and cook for 15 to 20 minutes until the rice is cooked.
Cut the foie gras into cubes and season with salt. Heat a frying pan until very hot and then colour the foie gras on all sides. Add the chestnuts to the pan and cook briefly. Remove the foie gras and the chestnuts from the pan and rest on kitchen paper to allow any excess grease to drain away.
Once the risotto is cooked, stir in the parmesan and the mascarpone. Season with salt and pepper if necessary.
Serve the risotto with the foie gras and chestnuts on top.
«Make sure the foie gras is well chilled before cooking. Heat the pan to very hot and then colour the foie gras quickly to prevent it from melting in the pan.»