Preheat your oven to 400°F (200°C). Dice the butternut squash and toss it in a bowl with olive oil, salt, and pepper until well-coated. Spread the squash evenly on a baking sheet and roast for 25-30 minutes.

In a medium saucepan, pour in the vegetable broth and heat it over medium-low until warm. Cover to keep the broth warm.

In a large skillet, add olive oil and sauté the chopped onion for about 4-5 minutes until translucent. Add minced garlic and cook for an additional minute.

Stir the Arborio rice into the skillet, ensuring each grain is coated. Toast the rice for approximately 2 minutes until slightly translucent at the edges.

Begin adding the warm vegetable broth to the skillet, one ladleful at a time, stirring continuously for about 20 minutes until creamy and al dente.

Gently fold in the roasted butternut squash, grated Parmesan cheese, and chopped sage leaves. Stir well, taste, and adjust seasoning before serving hot.