In a Large saucepan, melt butter: sauté; onion and garlic until soft. Add curry powder, salt coriander and red pepper; cook 1 minute. Add broth; boil gently, uncovered for 15 to 20 minutes. Stir in pumpkin and half & half; cook 5 minutes. Pour into blender container. Cover; blend until creamy. Serve warm or re-heat to desired temperature. Garnish with dollop of sour cream and chopped chives