In a large pot on high heat, melt butter and sauté chanterelles (reserving a few for garnish), potato, onions, celery and carrots until the onions become translucent, about 4 to 5 minutes. Add Dijon mustard, white wine, bay leaf and thyme and stir; add vegetable stock and bring to a boil for 5 minutes then let simmer for 30 minutes, until potatoes soften. Transfer to a blender and purée, then return soup back to the pot and add cream. Add more salt and pepper if needed.
Sauté reserved chanterelles in butter and use for garnish.
Makes 2 to 4 servings.