Heat avocado oil in a large skillet over medium-low heat. Add the onions add saute for 10 minutes. Sprinkle with salt and continue cooking, stirring occasionally, until golden brown and caramelized. This should take around 35-50 minutes. If the onions start to dry out or stick to the pan, add a splash of white wine or water. Remove from the heat and allow to cool before chopping into smaller pieces.

Add cashews, water, Worcestershire sauce, lemon juice, onion powder, and nutritional yeast to a high-speed blender. Blend the mixture, scraping down the sides of the blender as needed, until completely smooth and creamy.

Transfer the mixture into a medium bowl. Add the chopped caramelized onions, reserving some for topping, and season with salt and pepper. Stir until evenly mixed. Taste and adjust seasoning (salt, lemon, Worcestershire) to taste. Pop in the fridge for at least one hour before serving to allow the flavours to come together. Top with the remaining caramelized onions and sprinkle with fresh chopped parsley or chives if desired.