In a medium saucepan stir together the syrup and yolks, cook over low heat stirring constantly for 7-10 minutes or until thickened. Move to a clean bowl.
In a small pot add the water, sprinkle the gelatine over it and let sit for one minute. Over low heat heat until the gelatine dissolves but do not bring to a boil. Then stir the gelatine into the maple mixture. Let cool to room temperature, stirring occasionally, the mixture should resemble raw egg whites consistency. Then cover and chill 15 minutes.
Whip the cream until stiff, whisk ¼ into the maple mixture, then fold in the remaining whipped cream. Divide the mousse between six cups or bowls, chill two hours until firm. Top with whipped cream, chopped pecans and maple syrup if desired. Enjoy!
Notes
I stirred some chopped pecans into the mousse before chilling.
Can I make this dessert in advance?
Yes! Since this dessert needs time to chill you can make it up to 24 hours in advance. I would not make it more in advance than that though, as it can start to get watery.
How to store leftover maple mousse?
Store leftovers covered tightly with plastic wrap in the fridge for up to a day. After that it will start to get watery (but will still be delicious).