Heat the olive oil in a large pot over medium-high heat. When the oil is hot add in the shallots, carrots, and celery. Sauté for 3-4 minutes and then add in the garlic, salt and pepper and sauté another minute.

Add in the cauliflower florets, Italian seasoning, and nutmeg and stir everything together. 

Pour in the vegetable broth, and add in the parmesan cheese rind and sprigs of thyme. Bring the soup to a boil, cover it with a lid, and lower the heat letting it simmer for 20-25 minutes or until the cauliflower is tender.

Remove the parmesan cheese rind and thyme stems. Use and immersion stick blender and purée until smooth. Alternately, add the soup to a blender and blend until smooth. Put it back in the pot once puréed.

Pour the milk into the soup along with the parmesan cheese. Stir until fully incorporated and bring the soup back to a gentle simmer. Garnish with fresh thyme, parmesan cheese and croutons if desired.