Cut the squash in half lengthwise and scoop out the seeds. Coat both halves and the garlic with olive oil, then sprinkle on some salt and pepper. Roast them both until they’re tender and caramelized.
In the meantime, heat some more oil in a skillet over low. Caramelize the onions until they are golden brown, then remove them from the heat.
When the squash and garlic are cool enough to handle, scoop the flesh out of the squash and peel the garlic, then add them to a high-speed blender. Add the shallots, cashews, nutritional yeast, and seasonings, then blend the sauce with a bit of water until it’s smooth and creamy. Happy eating!