Place the chopped bacon in a large saute pan and bring over medium heat. Cook, stirring occasionally, until the bacon is crisp. Using a slotted spoon, transfer the bacon to a stack of paper towels to drain. Discard the bacon grease and wipe the pan clean.
Add the olive oil to the saute pan and bring over medium-high heat. Once the oil is hot, add the sliced sage and toss in the oil. Cook for 1 minute and then use a slotted spoon to remove the sage to the paper towels to drain. Add the onion and squash to the oil in the pan and sprinkle with salt and pepper. Stir to coat and cook for about 7 minutes, stirring occasionally. Add the garlic, stir and cook for another minute until the garlic is fragrant. Add the broth to the pan and bring the contents to a boil. Cover the pan and reduce the heat to a simmer for 15-20 minutes until the squash is tender.
While the squash is cooking, bring a separate pot of water to a boil and cook the linguine according to package instructions until al dente. *Remove one cup of the cooking liquid and set aside before draining the pasta*
When the squash is tender, allow it to cool for a couple minutes and then transfer the contents of the pan to a blender. Puree in the blender until smooth and combined. Add salt and/or pepper to taste if needed.
Combine the cooked, drained pasta, the squash sauce from the blender, ¼ cup of the reserved cooking liquid and the fresh spinach back in the saute pan and stir. Cook over medium heat, stirring occasionally, for 2-3 minutes until the spinach is wilted and the contents are heated through. Add additional reserved cooking liquid as desired for the sauce to coat the pasta (I added another ¼ cup or so). Stir in the parmesan cheese until melted and well combined. Top with the bacon and sage and serve.