Submerge cashews under water for at least an hour an up to 12 hours.
Fill a large pot with water and place over high heat. Once water begins to boil, add a small handful of salt and fettuccine. Cook paste until al dente, 6 to 8 minutes, stirring occasionally.
Remove pot from stovetop an drain. Return cooked fettuccine to pasta pot and set aside.
Place large skillet over medium-high heat and add 2 tablespoons oil.
Add onion and garlic and sauté for 3 to 4 minutes or until onions just begin to brown.
Add butternut squash and continue to sauté for 5 to 6 minutes. Season with salt and pepper.
Pour 1 cup broth/water over squash mixture and lower heat to medium. Cook until squash is fork tender and most of the liquid has evaporated.
Pour squash mixture into the well of a high powered blender. Drain cashews and add to blender.
Add all remaining sauce ingredients to blender and blend on high. With motor running add 2 tablespoons broth or water to blender, then add an additional 2 tablespoons at a time until sauce is smooth and creamy. Generously season with salt and pepper.
Pour sauce over pasta and fold together until pasta is completely coated.
Top coated pasta with fried sage and bacon. Serve.