Heat the olive oil in a large stockpot over medium-low heat. Add the onions and cook slowly for 15 to 20 minutes, stirring often, until they are lightly caramelized. Add the garlic, bay leaves and thyme. Cook for 1 minute. Add the white wine and cook for 5 to 7 minutes, until slightly reduced. Add the vegetable broth and bring to a boil. Reduce the heat and simmer for 20 minutes.
Add the balsamic vinegar and stir. Remove the bay leaves. Add salt and pepper, to taste.
Spoon the soup into four ovenproof serving dishes. Top each bowl with a slice of baguette, and sprinkle with ¼ cup (30 g) of the vegan cheese shreds. Place the bowls in the oven for 3 to 5 minutes, until the vegan cheese is melted and the baguette is slightly toasted.