Preparation / Directions:
Place egg whites in bowl. Attach bowl and wire whip. Turn to speed 8 and whip until stiff but not dry. Remove from bowl and set aside.
Place egg yolks and sugar in bowl. Attach bowl and wire whip. Turn to speed 6 and whip 1 minute or until thick and lemon colored. Stop and scrape bowl. Add oil and vanilla. Turn to speed 4 and whip 30 seconds. Gently fold egg whites into egg yolk mixture.
Sift flour, baking powder, and salt together. Fold half of flour mixture into egg mixture. Repeat with remaining flour.
Pour batter into a 10x15x1-inch jelly roll pan which has been lined with waxed paper, greased and floured. Bake at 375 F for 10 to 12 minutes. Immediately loosen cake from pan and invert onto a towel sprinkled with powdered sugar; cool completely.
Cut cake crosswise to form three 5x10x1-inch layers. Spread Lemond filling between layers. Cover cake tightly with plastic wrap and refrigerate at leat 4 hours. Frost and decorate with Lemon butter cream frosting.
LEMON FILLING: Combine egg yolks, sugar, and lemon juice in double broiler over boiling water. Cook, stirring constantly until mixture is very thick, about 5 minutes; do not boil. Remove from heat.
Add butter, 1 tablespoon at a time, beating utnil thoroughly incorporated. Stir in lemon peel. Cover mixture and refrigerate 1 hour.
Place cream in bowl. Attach bowl and wire whip. Turn to speed 10 and whip until stiff. Fold whipped cream into egg mixture. Refrigerate until ready to use.