Peel the squash using a vegetable peeler. Cut it in half lengthwise and remove the seeds using a spoon.
Chop the squash into bite sized pieces. Spread them out on a baking sheet lined with foil or a silicone baking mat.
Drizzle the squash with some oil and a sprinkle of salt and pepper. Toast to coat.
Roast the squash until it is fork tender, approximately 30-40 minutes.
Make the Risotto
While the squash is cooking, start the risotto. Place the stock in a small pot and heat over medium low. You want the stock to be warm when adding it to the risotto so that the temperature change does not affect the rice.
In a large pot, melt 3 Tablespoons of the butter over medium heat. When melted, add the red onion. Cook until the onion is translucent but not yet browning, approximately 3-5 minutes.
Add 2 Tablespoons of chopped fresh sage to the onion. Stir and cook until just fragrant, approximately 30 seconds.
Add the rice and stir. Continue cooking to slightly toast the rice until it is just starting to show a little brown color, approximately 3-5 minutes.
Add the white wine to the pot. Cook until the rice is almost dry, where most of the wine has been absorbed.
Add one cup of stock to the rice. Stir continuously until most of the stock has been absorbed. Repeat this process 1/2 cup of stock at a time until the rice is cooked thoroughly. You want the rice to have just a little bit of bite left so that it is not completely mushy. Depending on your rice, you may need more or less stock for the right consistency so start tasting the rice after 4 cups for firmness.
Assembly
When your squash is cooked through, remove from oven. Mash approximately half of the cubes to make a puree. Keep the other half of the squash as cubes.
Fry the sage by heating 3 Tablespoons of oil in a small skillet or pot and heat over medium heat. When hot, add the remaining fresh sage leaves. (Work in batches if needed, or use more oil to cook at once). Tilt the pot or skillet to submerge the leaves and remove when the edges are just crisp. Set aside.
When your rice is cooked, remove the pot from the heat. Add the rest of the butter, the Parmesan cheese, and the mashed butternut squash. It is important to do this before adding salt and pepper because the cheese is salty. Stir to combine.
Taste the risotto and season with additional salt and pepper as desired. Garnish with the remaining roasted butternut squash cubes and the fried sage. Serve immediately.
Notes
Get arborio rice online or in the rice section of your grocery store.Use any white wine that you enjoy drinking. I advise staying away from sweet wines as it will make the risotto very sweet as well. Chardonnay or sauvignon blanc are the ones I tend to use.The fried sage is completely optional but brings pockets of flavor and texture to the dish.A squash close to 3 pounds is best to get a good yield of mash and cubes, but anything in the 2-3 pound range works based on your preference.