Melt butter in 4 to 6 quart saucepan over medium high heat. Add onion and saute until soft and golden brown. Stir in pumpkin, stock, bay leaf, sugar, curry powder, nutmeg and parsley. Bring to simmer, then reduce heat and continue simmering uncovered for 15 minutes, stirring occasionally. Transfer soup in batches to blender or food processor and puree. Return to saucepan and add milk, and salt and pepper to taste. Simmer 5 to 10 minutes, but do not allow to boil. To serve hot, ladle into individual bowls. Float dollop of cream on each and sprinkle with paprika. Top with chives. To serve cold, chill soup thoroughly then ladle into individual bowls. Float tomato slice on top, cover with dollop of cream, and sprinkle with minced chives. Garnishes: 1/2 cup whipping cream, sour cream or yogurt; 1/2 cup minced chives or green onion; paprika ; 8 thin tomato slices (for chilled soup).