01 - Heat vegetable broth in a medium saucepan and maintain over low heat.
02 - Melt 2 tablespoons butter in a large heavy-bottomed skillet or Dutch oven over medium heat. Add onion and cook until translucent, approximately 3 minutes.
03 - Stir in minced garlic and cook for 1 minute. Add diced winter squash and cook, stirring occasionally, until it begins to soften, about 5 minutes.
04 - Incorporate Arborio rice and chopped sage, stirring continuously for 2 minutes to coat the rice and render it slightly translucent.
05 - Pour in white wine and stir until the liquid is mostly absorbed by the rice.
06 - Add warm broth one ladle at a time, stirring frequently. Permit each addition to be mostly absorbed before adding more. Continue until rice is creamy, al dente, and squash is tender, about 20 to 25 minutes.
07 - Remove from heat and stir in remaining 1 tablespoon butter, Parmesan cheese, and optional heavy cream. Season with salt and pepper to taste.
08 - Serve immediately, garnishing with extra Parmesan and fresh sage if desired.