In a large bowl pour in the heavy whipping cream and powdered sugar. Whip it on medium-high speed until it becomes thick and forms stiff peaks. This should take about 5 minutes.
In another bowl, add the lemon curd and carefully fold the whipped cream into the lemon curd until there are no more white streaks left.
Put the mousse into the desired glasses and place them in the fridge to chill for at least 30 minutes or overnight. Top with some extra whipped cream and enjoy!