Start whipping cream on medium speed in a stand mixer or with a hand mixer. Slowly add powdered sugar. Remove when stiff peaks form.
Set aside ¾ cup of whipped cream for later. Fold in ¾ cup lemon curd to the remaining whipped cream. You should have ¾ cup of curd left over.
Divide set-aside lemon curd between five glasses. Use something you can see through so you can see the layers - a lowball glass, wine glass, or champagne glass will work well. Spoon mousse into a piping bag, if desired, and pipe evenly on top of the lemon curd.
Add a dollop of whipped cream (2-3 tbsp) to the top of each (again, piped with a decorative tip if desired).
Refrigerate until ready to serve. Top with fresh berries just before serving (optional).