We found that Grade A dark amber maple syrup (in addition to maple sugar) gave this frosting the deep, rich taste we wanted. Curiously, Grade B syrup, which is typically more robust than Grade A, didn't give us as flavorful a result.
This recipe is an accompaniment for Maple Walnut Bûche de Nöel.
Active time: 20 min Start to finish: 35 min
Buttercream can be made 1 week ahead and chilled, covered, or 1 month ahead and frozen. Bring to room temperature (do not use a microwave) and beat with an electric mixer before using. The egg whites in this recipe will not be fully cooked, which may be of concern if there is a problem with salmonella in your area. You may want to use either pasteurized egg whites in the carton or reconstituted powdered egg whites.