After having washed the pumpkin, carefully remove all the peel, the seeds and the fibres. Cut into 1 cm square pieces. Finely cut the onion and the shallot. Melt the butter on a low heat with a drop of oil, fry the onion and the shallot. When they are soft but not golden, add the pumpkin: fry for a few moments and add the white wine and some of the broth., Add the herbs and salt and pepper to taste. Cook until the pumpkin is soft but has not become a pulp, add the chopped rosemary and remove from heat. Bring the broth to the boil and add the rice. As soon as it starts boiling again lower the heat until it is bubbling lightly. After 14 minutes add the rice to the pumpkin sauce, the Mascarpone cheese, some pepper and some more chopped rosemary. At 18 minutes remove rice from heat and cream with grated Parmesan cheese, and a touch of olive oil (depending on taste).