Warm the olive oil over medium high heat in a large pot. Add the onion and garlic, and cook for a few minutes until fragrant. Add the cauliflower, parsnips, thyme, salt, and pepper. Cook, stirring occasionally, for 5 to 7 minutes until slightly tender.
Add the whites beans and veggie broth to the pot. Increase heat to bring to a boil, cover, and reduce heat to a simmer for 20 to 25 minutes until the veggies are fork-tender.
Turn off the heat, and puree the soup using an immersion blender. Taste, and adjust seasonings as needed. If you don't have an immersion blender, transfer the soup in batches to an upright blender. Leave a corner of the lid cracked or remove the lid and cover loosely with a dish towel to let steam escape while blending. Be careful not to burn yourself.
Feel free to use roasted cauliflower and parsnips in place of raw if you have them on hand. You can skip the process of sautéing them. Frozen cauliflower also works in this recipe.
Leftovers will keep well in an airtight container in the fridge for up to 5 days. Reheat in the microwave or in a saucepan over medium-low heat until warmed through.
To freeze this soup, let it cool completely before transferring to freezer-safe containers. Be sure to leave a couple inches of headspace to allow the soup to expand during freezing. Use within 6 months. Let the soup thaw in the fridge overnight before serving.
Serve with crunchy bread, and garnish with more thyme leaves, pepper, and olive oil before serving. If you don't need this soup to be vegan, freshly grated parmesan cheese is a good addition.