01 - Preheat the oven to 400°F. Toss diced squash with 1 tbsp olive oil, salt, and pepper. Spread evenly on a baking sheet and roast for 20 to 25 minutes, turning once, until tender and golden. Set aside.
02 - Heat 2 tbsp butter and remaining 1 tbsp olive oil in a large sauté pan or Dutch oven over medium heat. Add sage leaves in a single layer and fry for 1 to 2 minutes until crisp. Remove with slotted spoon and drain on paper towels.
03 - Using the same pan, add onion and cook over medium heat for 4 to 5 minutes until soft and translucent. Stir in garlic and cook an additional minute.
04 - Add Arborio rice to the pan and cook for 2 minutes, stirring constantly until grains become glossy and well coated.
05 - Ladle warm vegetable stock into the rice mixture one cup at a time, stirring frequently and allowing liquid to absorb before adding the next. Continue for 18 to 20 minutes until the rice is creamy and al dente.
06 - Gently fold roasted butternut squash into the rice. Stir in remaining 2 tbsp butter and grated Parmesan. Season with salt and pepper to taste.
07 - Serve immediately, topped with crispy sage leaves and additional Parmesan if desired.