Preheat oven to 450°F. Line a baking sheet with aluminum foil, toss squash with balsamic vinegar, olive oil and salt on the sheet. Roast for 15 to 20 minutes or until the squash is tender, stirring/turning once. Set aside.
Cook the pasta according to package directions. Reserve one cup of pasta water for later, drain pasta. Cover and keep warm.
In a large skillet, over medium heat, sauté bacon until fat is rendered and bacon is crisp. Drain bacon on paper towel-lined plate and set aside.
Pour out all but one Tbsp of bacon drippings from the skillet, add garlic. Reduce heat and cook garlic for a minute, until lightly browned and fragrant. Add roasted squash, bacon and pasta to the skillet with the garlic and toss together. Add reserved pasta water, a little at a time, to the pasta mixture as needed to thin sauce(you may not need all of the pasta water).
Warm as needed over low heat to completely heat dish.
Serve warm with chopped sage, Parmesan cheese, and a sprinkle of balsamic vinegar if desired.