Heat the vegetable broth in a saucepan until just simmering, then remove from heat and keep warm.
In a large pan, heat olive oil over medium heat and sauté the chopped onion until it becomes translucent and fragrant, about 3-4 minutes.
Add the arborio rice to the pan, stirring constantly until it is lightly toasted and each grain is coated with oil, about 2 minutes.
Pour in the white wine and cook, stirring, until most of it has evaporated, about 2 minutes.
Carefully add a ladleful of warm broth and saffron, stirring constantly until the liquid is nearly absorbed.
Continue adding broth one ladleful at a time, allowing each addition to be absorbed before adding the next, stirring regularly. This process takes about 20 minutes until the rice is tender and creamy.
Stir in the roasted pumpkin puree, mixing well to incorporate the vibrant orange color and flavor evenly into the risotto.
Add the butter and grated Parmesan cheese, stirring until melted and combined, creating a rich, velvety texture.
Season with salt and pepper to taste, then remove from heat and let it rest for a minute to settle and thicken slightly.
Serve the pumpkin saffron risotto hot, garnished with extra Parmesan if desired and accompanied by crusty bread or leafy greens.
