Preheat your oven to 400°F (200°C). Spread the cubed butternut squash on a baking sheet, drizzle with a little olive oil, and season with salt. Roast for about 20-25 minutes until tender and lightly caramelized.
While the squash roasts, heat the vegetable broth in a saucepan until it's just simmering, then reduce to low heat to keep warm.
In a large skillet or saucepan, heat the olive oil over medium heat. Add the chopped onion and sauté until it becomes translucent and fragrant, about 3-4 minutes.
Add the minced garlic to the onions and cook for another minute until it releases a savory aroma, being careful not to burn it.
Stir in the Arborio rice and cook, stirring constantly, for about 2 minutes until the edges of the grains look slightly translucent.
Begin adding the warm broth, one ladleful at a time, stirring constantly and waiting until the liquid is mostly absorbed before adding more. Continue this process, maintaining a gentle simmer, for about 15 minutes.
Once the rice is creamy and just tender, gently fold in the roasted butternut squash pieces, allowing their sweet aroma to infuse the dish.
Add the chopped spinach and stir until wilted and vibrant green, about 2 minutes.
Season the risotto with salt and pepper to taste, then stir in the grated Parmesan cheese for a silky finish.
Cook for another 2-3 minutes, ensuring everything is heated through and well combined.
Serve the risotto hot, garnished with extra Parmesan or a drizzle of olive oil if desired, and enjoy the comforting seasonal flavors.