Heat a wide, heavy-bottomed pan over medium heat and add a splash of olive oil. Once it shimmers and starts to ripple, add the finely chopped onion.
Cook the onion, stirring occasionally, until it becomes soft, fragrant, and beginning to caramelize around the edges, about 8 minutes.
Stir in the pumpkin purée, mixing well to incorporate it with the caramelized onion. Let it warm through for about 2 minutes, filling the kitchen with a sweet, earthy aroma.
Add the Arborio rice to the pan, stirring constantly to coat each grain with the pumpkin mixture. Cook until the rice turns glossy and slightly translucent at the edges, about 2 minutes.
Pour in a ladleful of warm vegetable broth, stirring steadily. Wait until most of it is absorbed before adding the next ladleful. Continue this process, stirring and adding broth gradually, for about 20 minutes, until the rice is tender yet retains a slight bite.
Once the risotto reaches a creamy consistency and the rice is al dente, stir in the grated Parmesan cheese and a pinch of nutmeg. Adjust seasoning with salt and pepper to taste.
Remove from heat and let the risotto sit for a minute, allowing flavors to meld and the texture to settle into a luscious, velvety finish.
Serve the pumpkin risotto hot, garnished with extra Parmesan or fresh herbs if desired, and enjoy the cozy, comforting flavors.
