Put the cauliflower in a large saucepan and add enough water to come up about two-thirds of the way (about 3 cups/720 ml). Add the salt, cover, and bring to a boil over high heat, then lower the heat and simmer until very tender, about 15 minutes. Add the cream and garlic. With an immersion blender, puree until smooth. Stir in more salt, if needed, then serve.