Melt butter in a dutch oven. Saute onion until soft. Add ginger and garlic and saute for 1 minute. Add carrot and saute for 1 minute. Add enough broth to cover. Simmer until carrots are soft (about 30 minutes). In batches, puree in food processor until smooth. Stir in cream and reheat to boiling. Stir in salt and pepper.