Heat up a tablespoon of neutral tasting oil in a Dutch oven / soup pot. ( Omit the oil and use ¼ cup of vegetable broth instead to make it oil-free. ) Place in the onion and saute for 3-4 minutes, or until translucent.
Next, add in the garlic together with the thyme and rosemary, if using. Saute for another 1-2 minutes, until fragrant.
Add in the cauliflower, potato, bay leaves and broth into the pot. Bring it to a boil, then lower the heat to a gentle simmer. Cook with the lid on for 10-15 minutes, or until the veggies are tender, stirring every 5 minutes.
Stir in the nutritional yeast and puree the soup until smooth. Alternatively, you can puree them in a blender, but be caution when handling hot liquids.
Bring the soup to a boil once more. Add in the carrot and broccoli and cook for another 8-10 minutes, or until the broccoli and carrot have softened.
Serve it up and enjoy while hot !