Cut the pumpkin in half and remove the seeds. Cut the flesh and skin into 1 cm pieces. Fill 1 cup with pumpkin pieces and set aside. Cook the remaining pieces for approx. 5 minutes until they are soft. Then strain/puree and set aside.
Melt 4 tablespoons of butter in a thick-bottomed pan over a medium heat and sauté the shallot until translucent. Then add the raw pumpkin pieces and season with salt and pepper. Fry for 2 minutes, then add the rice and stir constantly for a minute - until the rice is translucent.
Now slowly add the stock one ladleful at a time and stir well. Only add more stock when the liquid has completely reduced. The rice must never be allowed to overcook.
After about 20 minutes, when the rice is gradually softening and the stock has reduced completely, mix the pumpkin puree, the remaining butter and the grated Grana Padano into the risotto.