In skillet, melt butter and saute onions and whole morels for about 10 minutes. Stir in flour and cook 2 to 3 more minutes. Stir in broth until well blended. Add half and half. Simmer for 20 minutes- do not let boil. Cool 5 minutes. Blend in food processor or blender. Add the sherry, salt, and pepper to taste. Sprinkle chives or parsley on top.