Cut the pumpkin into pieces, put them into a baking tray seasoning it with a little bit of salt and pepper. Cover the tray with tinfoil and roast it for one hour at 180°C in the oven. Let the cooked pumpkin cool down, peel off the skin and blend the pulp in the mixer.
Soft the finely chopped onion in a pan with half of the butter. Add the rice and roast it over a high flame for 2-3 minutes, then deglaze with the white wine. Melt the Gorgonzola in a small pot with two tablespoons of milk. Let it cool down and add the two egg yolks. Gradually add the vegetable broth, always letting the rice absorb it before you add more.
Halfway through the cooking process add the pumpkin pulp, the Gorgonzola cream and the twig of sage. Mix all ingredients well and taste the rice. If it is not yet cooked, add more broth. Turn off the flame, take out the sage from the risotto and finalize it with the rest of the butter and the Parmigiano.