Heat a large skillet over medium-low heat and add the bacon. Cook until the fat is rendered and the bacon is crispy. Once crispy, remove it with a slotted spoon and place it on a paper towel-lined plate to drain any excess grease.
Remove about 2 tablespoons of the bacon grease from the skillet and reserve it for the risotto. Add the butternut squash cubes to the skillet with a sprinkle of salt and pepper and the nutmeg. Cook, stirring occasionally, until the squash is just fork tender (you don’t want it to be mushy!).
Heat a saucepan or pot over medium-low heat and add the reserved bacon grease. Add the arborio rice and stir. Toast the rice until the pieces are translucent and fragrant. Stir in the garlic and cook for another minute. Stir in the white wine, constantly stirring or at least stirring every minute or so, until the rice absorbs the wine. Once the wine is absorbed, add in 1 1/2 cups of the stock, stirring until the rice absorbs the liquid like it did with the wine. Repeat this 2 to 3 more times, until all stock has been added and the rice is al dente. You want it to appear “hydrated” – and want there to be some liquid left when serving. This process should take about 15 to 20 minutes.
Once the rice is cooked, stir in the butternut squash cubes, parmesan cheese and almost all over the bacon, leaving some for the topping. Top with a bunch of fresh sage (you can stir some in if you want, it will get incorporated once you serve the risotto) and parmesan shavings. Serve immediately.