Lemon Meringue Cake

For Cake:

Heat oven to 350º F / 175º C. Grease and dust with flour 2 round 9 x 1 1/2 inch cake pans.

Combine sour cream and milk; set aside.

In a large mixing bowl on high speed, mix butter, sugar, eggs, lemon extract, lemon juice and rind until fluffy; scrape sides of bowl occasionally and continue to mix for 5 minutes. Sift flour, baking powder and salt together; add to creamed mixture alternately with sour cream mixture. Pour batter into prepared pans. Bake until wooden pick inserted in center comes out clean, 30 to 35 minutes. Cool layers 10 minutes; remove from pans and cool completely.

For Lemon Filling:

Meanwhile, combine 1 cup sugar, cornstarch and salt in medium size heavy saucepan. Gradually stir in water, lemon juice, butter, and rind. Cook over medium heat until mixture boils and thickens, stirring constantly. Remove from heat. Beat egg yolks slightly; gradually stir in about 1/4 of hot lemon mixture into egg yolks. Return egg yolk mixture to saucepan and cook 2 to 3 minutes, stirring constantly. Let cool.

For Meringue:

Beat egg whites, cream of tartar and vanilla until foamy in large mixer bowl. Gradually add 3/4 cup of sugar, beating until stiff peaks form.

To Assemble Cake:

Heat oven to 450º F / 230º C.

Place 1 layer on oven-proof serving plate; spread lemon filling and 1/3 meringue; top with second layer of cake. Spread remaining meringue on top of cake.