In small saucepan, bring maple syrup, brown sugar and 1⁄4 cup of the heavy cream to a simmer over medium-low heat. Stir occasionally until sugar has dissolved and mixture is smooth.

Beat egg yolks in heatproof bowl. While whisking constantly, very slowly pour about 2 tbsp of the hot syrup mixture into yolks. Continue whisking and slowly pour in remaining syrup mixture.

Return mixture to saucepan and cook over medium-low heat, stirring constantly, until it thickens slightly, about 3 minutes. Remove from heat and transfer to large bowl. Let it cool for 15 to 20 minutes, or use an ice bath to speed up the process.

In separate bowl, whip the remaining 13⁄4 cups heavy cream until stiff peaks form. Set aside.

In clean bowl, beat egg whites until stiff peaks form.

Gently fold whipped cream into cooled sugar mixture using rubber spatula, mixing until smooth. Then gently fold in whipped egg whites.

Spoon mousse into serving dishes and place in freezer for at least 1 hour.

Just before serving, sprinkle remaining brown sugar on top of each mousse and use a kitchen torch to lightly caramelize it, adding a delicious crunch.