01 - Heat olive oil and 1 tablespoon butter in a large heavy-bottomed saucepan over medium heat. Add onion and cook until softened and translucent, about 3 minutes.
02 - Stir in garlic and diced squash. Cook, stirring occasionally, until squash begins to soften, about 5 minutes.
03 - Add Arborio rice and cook, stirring constantly, for 2 minutes until grains are well coated and slightly translucent at edges.
04 - Pour in white wine and cook, stirring, until mostly absorbed.
05 - Begin adding warm vegetable broth one ladleful at a time, stirring frequently. Wait until most liquid is absorbed before adding more. Continue until rice is creamy and al dente and squash is very tender, about 20-25 minutes. You may not need all the broth.
06 - Stir in chopped sage, remaining butter, Parmesan cheese, and heavy cream if using. Season with salt and pepper to taste.
07 - Remove from heat, cover, and let rest for 2 minutes. Serve hot, garnished with extra Parmesan and sage leaves.