Preheat the oven to 400ºF. Slice the butternut squash in half through the long side. Set both halves cut side up on a baking sheet lined with foil. Roast in the oven until the squash is tender. (This could be more or less time, depending on the size of your squash. You can check to see if it is done by piercing it with a fork. It will be soft when it is done.) Remove from the oven and allow the squash to cool.

When the squash is cool, scoop the flesh and place in a food processor. Process until smooth. Weigh out 12 oz of the puree. Reserve the remaining squash for another recipe.

Heat the chicken broth and the water in a saucepan over medium heat. Once hot, turn the heat down to low.

Heat the olive oil in a large skillet or Dutch oven. Add the onion and cook until softened, about 2 minutes. Add the garlic and cook an additional 30 seconds. Add the rice and toast, stirring, for 3 minutes.

Add 2 ladlefuls of the warm broth to the pan and stir until the broth evaporates. Repeat with the remaining broth, cooking until the risotto is creamy. This will take about 20 minutes. 

During the last few minutes of cooking, add the butternut squash puree. Season with nutmeg, salt and pepper.

Remove the pot from the heat and stir in the butter and the cheese and stir to combine. Serve topped with the sage.