Whip the cream with the scrapings from the vanilla bean until stiff and chill. In a small saucepan, boil the maple syrup to soft ball stage or 238 degrees on a candy thermometer. (Because there is such a small amount of maple syrup, measuring the temperature with a thermometer may be difficult. In this case, a good way to tell if the syrup is ready is to dip a spoon into the boiling maple syrup then put a drop into a cup of ice water. If the syrup dissolves it?s not ready. If it holds its shape and is slightly pliable between your thumb and finger, it's ready.)
Sprinkle the gelatin over the cold water and let it sponge. Place the whites in a clean dry bowl and, using a whip attachment, whip until almost stiff. Hold them with the whip turning on low until the maple syrup is up to temperature. When the syrup is ready, take it off the stove and, with the mixer on high, drizzle it down the wall of the mixing bowl into the whites. Warm the sponged gelatin in the microwave and drizzle it into the whites as well. Continue whipping until the meringue is cooled. Fold in the whipped cream and pipe or spoon the mousse into dessert glasses and chill for 1 hour or until set.
Recipe courtesy of Mario Batali