Heat 1 tablespoon of butter in a large pan over medium heat. Add diced onions and garlic, sautéing until soft.
Add the diced pumpkin to the pan, cooking for 5-7 minutes until it softens.
Stir in the Arborio rice and cook for another 2-3 minutes, until the rice is lightly toasted.
Pour in the white wine (or broth) and stir until absorbed.
Gradually add the stock, one ladle at a time, stirring constantly and letting the liquid absorb before adding more.
Once the rice is tender (about 18-20 minutes), stir in the remaining butter, sage, and parmesan.
Season with salt and pepper to taste.
For crispy sage: In a separate pan, melt butter and fry sage leaves until crispy, then top risotto with them (optional).