Preheat oven to 375°F. Toss 1 ¾ cup of the butternut squash with 2 tablespoons of olive oil and bake on a baking tray for 25 minutes, set aside.
Combine remaining ¼ cup of raw butternut squash with 3 cups vegetable broth in a blender and blend until well pureed, pour over the rice and let stand for 10 minutes, stirring occasionally. Drain the rice, keeping the broth mixture separately, and let stand for 10 minutes.
Heat remaining 3 tablespoons olive oil in a pot over medium high heat; add the sage and fry briefly, about 15 seconds. Add the drained rice followed quickly by the onion and garlic, stir to toast rice, about 1 minute. Add the previously strained liquid, salt, and black pepper to the pot and bring to a boil, reduce to a very low simmer. Cover pot and simmer until all the liquid has been absorbed, about 7-10 minutes, stirring 1-2 times.
Add the parmesan cheese, roasted squash, and remaining 1 cup of broth, stir until cheese has fully melted. Serve immediately.