1. Preheat the oven to 425 degrees F. In a large bowl, toss cauliflower, garlic, shallots, onion, and potato with olive oil. Spread out in a roasting pan or baking sheet with sides and roast in oven until roasted and lightly browned, about 30 minutes. Be sure to check on veggies periodically and move them around with a spatula to prevent them from burning.
2. When the vegetables are ready, transfer to a large pot and pour in the vegetable stock, bay leaf, thyme, cumin, and the chipotle pepper. Bring to a boil and cook at medium heat for 30 minutes. Remove and discard the bay leaf.
3. Stir in the soy milk and then using an immersion blender, puree the soup in the pot or transfer to a blender or food processor (be careful!) and puree in batches, then return to the pot.
4. Season with salt and pepper. Heat through before serving but avoid boiling.
Note: Avoid using too many chipotle peppers until you understand how spicy they are.