Warm vegan butter in a large pot over medium heat.
Add onions, celery, and carrots. Cook until softened and lightly colored.
Stir in garlic, salt, and pepper. Add flour and cook 1 minute.
Slowly whisk in plant-based milk, removing lumps.
Add broth, potatoes, nutmeg, and bay leaf. Stir well.
Simmer 30 minutes until potatoes are soft and creamy.
Adjust seasoning and add extra broth if thinner consistency desired.
Serve hot with herbs, vegan sour cream, or toppings of choice.
