In a large soup pot over medium heat, warm the olive oil. Add the leeks and sauté, stirring constantly, until tender, about 5 minutes. Add the cauliflower and sauté for about 5 minutes. Add the stock, cream, bay leaf and coriander, bring to a simmer and reduce the heat to medium-low. Simmer, stirring occasionally, until the cauliflower is very tender, about 45 minutes. Remove the bay leaf.
Using a stick blender, puree the soup directly in the pot until it is very smooth and creamy. Alternatively puree in blender in batches. Season with salt and white pepper. Keep the soup warm over low heat until ready to serve.
Ladle the soup into warmed individual bowls and garnish with a pinch of chives. Serve immediately.