Peel and thinly slice the onions.
Heat the oil in a pot.
Add the onions, garlic, bay leaves, thyme, and salt and pepper and cook until the onions are very soft and caramelized, for about 25 minutes.
Add the beer/wine, bring to a boil, reduce the heat and simmer until the wine has evaporated - about 5 minutes. Discard the bay leaves and thyme sprigs.
Add the flour/cornstarch and stir. Turn the heat on medium-low. Cook for 5 minutes, while stirring.
Add the veggie broth. Bring the soup back to a simmer, and cook for 10 minutes. Season, to taste, with salt and pepper.
Add a slice of bread in a pan and toast it on one side without burning. Flip it on the other side and place a slice of vegan cheese on top and cover with a lid. Let it melt at low temp for 1-2 minutes.
Serve hot, with the toast and cheese in the middle.