When making frosting, substitute 2 tablespoons fresh lemon juice for the vanilla extract.
A few changes to our basic vanilla cake recipe turn it into this sunny lemon version. Reserve the egg whites left over from the cake for the frosting.
To make the recipe Martha prepared with John Barricelli on "The Martha Stewart Show," follow these instructions immediately before frosting the cake: Place one cake, bottom side up, on a cake stand. Tuck strips of parchment paper underneath. Using an offset-spatula or table knife, spread top with lemon curd. Top with remaining cake; continue frosting top and sides as directed.