Lemon Curd Cake

Directions

1. In a large heavy saucepan, mix sugar and cornstarch. Whisk in lemon juice and zest. Cook and stir over medium heat until thickened and bubbly. Reduce heat to low; cook and stir 2 minutes longer. Remove from heat.
2. In a small bowl, whisk a small amount of hot mixture into egg yolks; return all to pan, whisking constantly. Add butter; cook over medium heat, whisking constantly, until mixture is just thick enough to coat a metal spoon and a thermometer reads at least 170°. Do not allow to boil. Remove from heat immediately. Transfer to a small bowl; cool. Press plastic wrap onto surface of custard. Refrigerate until cold.
3. Preheat oven to 350°. Line three 9-in. round baking pans with parchment paper.
4. In a large bowl, beat oil, sugar, egg yolks and vanilla until well blended. In a small bowl, combine flour, baking powder and salt. In another small bowl, combine buttermilk, lemon juice and lemon zest. Add dry ingredients to sugar mixture alternately with buttermilk mixture, beating well after each addition. In a large bowl, beat egg whites until stiff peaks form; fold into batter. Bake until a toothpick comes out clean, 25-30 minutes. Cool in pans for 10 minutes on wire racks. Remove from pans and cool completely.
5. In a large bowl, beat cream cheese and butter on medium speed until smooth, 3-4 minutes. Reduce mixer speed to low; beat in confectioners' sugar, lemon juice and lemon zest until fluffy, 2-3 minutes.
6. Place 1 cake layer on a serving plate; spread with 1/2 cup lemon curd. Top with 1/2 cup frosting. Repeat layers. Top with remaining cake layer. Frost top and sides of cake with remaining frosting.