Fill a medium pot with salted water (about 4 quarts) and bring to a boil. Add butternut squash to boiling water. Cook for 10 minutes, until fork tender.
Use a strainer to remove and place the cooked butternut squash in a high-speed blender or food processor. Leave the water to boil the pasta and cook according to the packaging instructions.
Add, cashews, water, maple syrup, salt, pepper, and caramelized onions to blender on the highest speed until perfectly smooth and creamy. Adjust seasoning as needed. Pour immediately overtop cooked pasta.
Garnish with more caramelized onions and serve immediately while hot.