On medium heat sweat the three cups diced onions in two tablespoons of butter for twenty five minutes, or until tender. Season with salt and white pepper. Toast the pinch of saffron threads in a dry sauce pan for thirty seconds over medium heat, add the two cups wine to the saffron threads, and quickly bring to a simmer, turn off the heat, and allow the saffron to steep in the wine for five minutes, strain through a fine meshed sieve reserving the liquid. Add the three cups carnaroli rice to the sautéed onions and toast for three minutes, pour in the two cups saffron infused wine and reduce to a glaze. Begin moistening the rice with chicken stock which you have previously brought to a simmer, add just enough stock to cover, allowing it to reduce, stirring frequently, adding a little broth at a time to keep the rice moist and slowly bubbling. Cook in this manner for about thirty minutes. Taste for doneness, continue cooking until the rice grains are translucent while still having a very slight bight, remembering that the risotto will continue to cook once you have turned off the heat. Once you feel the rice is just right, take off the heat, beat in two cups warm pumpkin puree, two tablespoons butter, two tablespoons mascarpone, and two tablespoons parmesan. Taste and adjust final seasoning.
French Red Pumpkin Puree:
Split french red pumpkin in half and scoop out the seeds. Quarter the pumpkin, and place the pieces skin side down in a casserole. Liberally brush the interior with butter, season with salt and pepper,
and scatter fresh sage leaves over the flesh of the pumpkins. Tightly cover with foil and bake at 350 degrees until the flesh if fork tender, about two hours. Flesh out the pumpkins discarding the skin and sage leaves and blend in a food processor until smooth. Season with salt and pepper and reserve.
Garnish:
Place a large sauté pan over high heat, add two tablespoons of butter and allow to foam. Once foamy add the diced squash, walnuts, and sage leaves cooking until caramelized and tender. Place the risotto into the bowls. Top with the sautéed pumpkn, walnuts and sage. Grate fresh nutmeg over top to finish.