Place homemade curd or 1 cup of pre-made lemon curd in a large bowl. In a large metal or glass bowl, beat the egg whites with an electric mixer until foamy. Add the sugar and continue beating on high speed until whites are glossy and hold stiff peaks.
Using a spatula, gently fold 1/3 of the egg whites into the lemon curd. To fold, cut the spatula down the middle of the bowl, bringing it up along the bottom and edge and gently fold over the top. Turn the bowl 90 degrees and repeat until only a few streaks of egg whites remain. Repeat with half of the remaining whites, then the rest.
In the same bowl that you whipped the egg whites, place the whipping cream and vanilla. Beat with the electric mixer on high speed until the cream holds stiff peaks. Fold into the curd mixture 1/4 at a time, using the same method as for the egg whites.
Serve chilled mousse layered with an assortment of fresh berries.
Notes
This recipe uses raw egg whites - use only pasteurized eggs in this recipe for safety. You may substitute 1 cup of pre-made lemon curd for the homemade curd in this recipe.