Heat the broth in a separate pot and keep it simmering.
Heat the oil in a large pan and sauté the chopped onion until softened and translucent.
Add the pumpkin cubes to the pan and cook for approximately 2-3 minutes.
Pour in the white wine and let it evaporate completely.
Begin adding the hot broth one ladle at a time, stirring frequently and waiting for each addition to be absorbed before adding the next, for about 18-20 minutes total until the rice is creamy and al dente.
Remove from heat and stir in the butter and grated Parmigiano Reggiano.
Season with salt, pepper, and a pinch of nutmeg to taste.
