- Whip the egg whites with the cream of tartar until foamy, then add the sugar and whip the whites just to the soft peak.
- Bring the maple syrup to a boil and cook uncovered and without stirring until it reaches a temperature of 242 °F (117 °C) on a candy thermometer. While beating on medium speed, carefully pour the maple syrup into the meringue by pouring it down the side of the bowl (this will help prevent splashing of hot syrup) and continue whipping until the mixture has cooled but is not quite room temperature, about 3 minutes. Stir in the vanilla. This frosting should be used immediately after making.
Recipe from Back to Baking, Anna Olson, Whitecap Books, 2011