2 1/4 c. all purpose flour
1 2/3 c. sugar
3 1/2 tsp. baking powder
1 tsp. salt
1 1/4 c. milk
2/3 c. shortening
1 tsp. vanilla
5 egg whites

LEMON FILLING:

3/4 c. sugar
3 tbsp. cornstarch
1/4 tsp. salt
3/4 c. water
1 tsp. grated lemon peel
1 tbsp. lemon juice
4 drops yellow food color, if desired
1 tbsp. butter

Heat oven to 350 degrees. Grease and flour 2 round pans or rectangle pan (13 x 9 inch). Beat flour, sugar, baking powder, salt, milk, shortening and vanilla in large mixer bowl on low speed, scraping bowl constantly, 30 seconds. Beat on high speed, scraping bowl occasionally, 2 minutes. Beat in egg whites on high speed, scraping bowl occasionally, 2 minutes. Pour into pans. Bake until toothpick comes out clean or until it springs back. Layers 30-35 minutes. Rectangle 40-45 minutes.

Filling: Mix sugar, cornstarch and salt in saucepan. Stir in water gradually. Cook, stirring constantly until mixture thickens and boils. Boil and stir 1 minute. Remove from heat; add lemon peel and butter. Stir in lemon juice and color, cool. If too soft, refrigerate until set.