4 c. cake flour OR
3 1/2 c. all-purpose flour
1 tsp. baking soda
1/2 tsp. baking powder
1 c. butter
3 c. sugar
2 tsp. lemon extract
2 c. buttermilk or sour milk
6 egg whites

Stir together flour, soda, and baking powder. In large mixing bowl beat butter on high speed of electric mixer for 30 seconds. Add sugar; beat until fluffy. Beat in extract.

Add flour mixture and buttermilk alternately, beating after each addition. Add egg whites; beat at medium speed for 2 minutes.

Divide among 3 waxed-paper-lined 9 x 1 1/2-inch round baking pans. Bake in a 350 degree oven about 30 minutes. Cool in pans for 10 minutes; remove from pans. Cool on wire racks.

Prepare Filling and Frosting. Set aside 1/4 cup Filling. Place 1 cake layer on serving plate. Spread with half of Filling. Add second cake layer; spread remaining Filling atop. Add third layer.

Frost cake; drizzle with reserved Filling. Garnish with lemon slices, if desired. Makes 12 servings.

FILLING:

1 c. sugar
1/4 c. cornstarch
1/4 tsp. salt
1 c. water
3 egg yolks
1 tbsp. butter
4 tsp. lemon peel, shredded
1/2 c. lemon juice

In saucepan combine sugar, cornstarch, and salt. Gradually stir in water. Cook and stir until thickened and bubbly; cook and stir 2 minutes more. Gradually stir about half of the hot mixture into egg yolks. Return all to saucepan; cook and stir 2 minutes.

Remove from heat; stir in butter and lemon peel. Stir in lemon juice. Cover with plastic wrap; cool.

FROSTING:

1 c. milk
3 tbsp. all-purpose flour
1 c. butter
1 c. sugar

In small saucepan combine milk and flour. Cook and stir until thickened; cook and stir 1 minute more. Cover with plastic wrap; cool. In small mixing bowl beat butter for 30 seconds. Add sugar; beat until fluffy. Add cooled milk mixture; beat until fluffy.