Preheat oven to 400F with rack on middle position. Peel and cube butternut squash into 3/4 inch cubes. Line a baking sheet with foil and spread squash out over the baking sheet; toss with olive oil, 1 tsp kosher salt, 1/2 tsp black pepper, and roast for 25 minutes or until fork-tender. Remove from heat and set aside.
In a heavy pot or Dutch oven, saute the butter, bacon, and onions on medium low until cooked through and translucent, about 10 min, stirring often. Add rice and garlic. Stir to coat well. Add wine and cook 2 minutes. Add 2 cups of chicken stock to the rice, with 1 tsp kosher salt and 1/2 tsp black pepper. Stir and simmer until stock is almost fully absorbed, 5-10 min.
Continue simmering and adding 1 cup of stock at a time, stirring very few minutes. The key is to keep adding liquid and letting rice fully absorb it, a cupful at a time. It takes about 30 minutes for rice to be tender and all of the broth has been used/absorbed. Remove from heat, gently toss in roasted squash, parsley, and parmesan cheese. Serve immediately.