Heat the olive oil in a large stockpot. Add the garlic and shallots and saute on low heat for about five minutes or until translucent. Add the cauliflower and cook for another five minutes, ensuring that the cauliflower is evenly coated with the oil. Add the vegetable broth and coconut milk and bring the mixture to a boil. Reduce heat to simmer and cook, uncovered, for 30 minutes until cauliflower is soft and the soup is slightly reduced. Remove from heat and puree with a food processor or immersion blender. Add salt, adjusting for taste. Re-heat if necessary and serve.