In a medium pot add chopped berries, sugar, lemon juice, water and cornstarch. Bring to a boil and stirring constantly cook until thickened. Move to a clean bowl and let cool completely.
Beat egg whites until soft peaks form. Add sugar a tablespoon at a time while beating until stiff peaks form. Place a cake layer on the bottom of a cake pan, spread with the cooled berry filling and top with meringue. Bake.