Heat the vegan butter in a large soup pot on medium high. Add all the thinly sliced onions and start to saute them. Stirring constantly. Sprinkle with a bit of salt and pepper. Saute until they are translucent, reducing heat as needed. About 5 minutes.
Now, reduce heat to medium low, and continue to cook until fully caramelized. Stirring every few minutes. It will take about 30-45 minutes to caramelize the onions. You know they are done when they are very brown and could melt in your mouth.
Once the onions are caramelized, add the garlic, bay leaves, thyme, diced potatoes and white wine(if using). Simmer for about 10 minutes or until the wine is mostly absorbed by the onions and potatoes.
While the wine cooks, make cashew cream. Drain the raw cashews that you soaked for at least 8 hours in cold water, I like to do it overnight. If you are in a pinch, you can soak them in boiling water for 15-30 minutes. Add the drained cashews to a blender with 1 cup of the vegetable broth, the nutritional yeast, lemon juice and a pinch of salt and pepper. Blend on high until it is completely smooth.
Next, add the corn starch to the pot and toss to coat the potatoes and onions.
Then add the remaining 7 cups of vegetable broth and the cashew cream you made to the pot. Stir to combine. Season with a few pinches of salt and pepper.
Simmer on medium low, just so it is at a small bubble for about 20 minutes or until the potatoes are cooked through. Taste and adjust seasonings. Serve with oyster crackers on top.