Melt the butter in a heavy casserole dish or stockpot. Add leeks and thyme. Cook over low heat until soft.

Add potatoes and vegetable stock. Season with salt and pepper. When the potatoes are soft, add cream and bring to a boil.

Transfer contents to a blender in batches and carefully blend until smooth. (Make sure to cover the blender lid with a kitchen towel.)

Add goat cheese to the last batch of soup to be blended.  Strain soup to remove lumps.  Add more salt and pepper if needed. If soup is too thick, thin with water.

Garnish with lemon zest and lobster meat. Or garnish with black truffles or sliced smoked duck.