Peel and grate the butternut squash, then mix with salt, black pepper, garlic powder, and onion powder. Let sit for 10 minutes.
Squeeze out excess moisture from the grated squash, then mix in flour, beaten egg, Parmesan cheese, and green onions until well combined.
Form the mixture into small patties about 2-3 inches in diameter.
Heat vegetable oil in a skillet over medium heat. Fry the fritters for 3-4 minutes on each side until golden brown and crispy.
Remove fritters from the skillet and place on a paper towel-lined plate to drain excess oil.