Preheat oven to 400°F (200°C). Toss diced butternut squash with 1 tbsp olive oil, 1/2 tsp salt, and 1/4 tsp pepper on a baking sheet. Roast for 20-25 minutes, or until tender and slightly caramelized, flipping halfway through. Set aside.

While the squash roasts, gently heat the vegetable broth in a small saucepan over low heat. Keep it warm throughout the cooking process.

In a large, heavy-bottomed pot or Dutch oven, heat 2 tbsp olive oil and 1 tbsp butter over medium heat. Add the chopped onion and cook until softened and translucent, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant.

Add the Arborio rice to the pot with the onions and garlic. Stir continuously for 2-3 minutes until the edges of the rice grains become translucent, but not brown.

Pour in the white wine and stir until it is completely absorbed by the rice, about 2-3 minutes.

Begin adding the warm vegetable broth, one ladleful (about 1/2 cup) at a time, stirring constantly. Wait until each ladleful of broth is almost fully absorbed by the rice before adding the next. This process usually takes about 20-25 minutes. The rice should be creamy and al dente (tender with a slight bite in the center).

Once the risotto has reached the desired consistency and the rice is cooked, remove the pot from the heat. Stir in the roasted butternut squash, 1/4 cup grated Parmesan cheese, 2 tbsp unsalted butter, and the chopped fresh sage. Stir vigorously to incorporate, creating a creamy texture.

Taste and adjust seasoning with salt and black pepper as needed. Let the risotto rest for 2 minutes, covered, before serving. Garnish with additional Parmesan cheese and a few whole sage leaves, if desired.