LEMON LAYER CAKE WITH LEMON CURD AND MASCARPONE

Steps:

• For lemon curd:
• Whisk first 4 ingredients in medium metal bowl. Set bowl over saucepan of simmering water (do not allow bottom of bowl to touch water). Whisk constantly until thickened and instant-read thermometer inserted into mixture registers 160°F, about 10 minutes. Remove bowl from over water. Add butter; whisk until melted. Transfer 1 cup curd to small bowl for spreading on cake layers. Reserve remaining curd for filling. Press plastic wrap directly onto surface of both curds. Chill overnight. (Can be made 3 days ahead. Keep chilled.)
• For cake:
• Position rack in center of oven and preheat to 375°F. Line bottom of two 9-inch-diameter cake pans with 1 1/2-inch-high sides with parchment paper (do not grease pans or parchment). Using electric mixer, beat egg yolks and 7 tablespoons sugar in large bowl until mixture is very thick and slowly dissolving ribbons form when beaters are lifted, about 4 minutes. Using clean dry beaters, beat whites in another large bowl until soft peaks form. Add remaining 7 tablespoons sugar, 1 tablespoon at a time, beating until stiff and glossy. Fold half of whites into yolk mixture, then sift half of flour and 1/4 teaspoon salt over and gently fold in until incorporated. Fold in remaining whites, then sift remaining flour over and fold in just until combined, being careful not to deflate batter.
• Divide batter between pans; smooth tops. Bake until tester inserted into center of cakes comes out clean, about 15 minutes. Cool in pans on racks.
• Run knife around edge of pans to loosen cakes. Invert cakes onto 9-inch-diameter cardboard rounds, tapping on work surface if necessary to release cakes. Cut each cake horizontally in half (layers will be thin). Peel off parchment.
• For syrup:
• Place sugar in small metal bowl. Add 1/2 cup boiling water; stir to dissolve sugar. Stir in lemon juice.
• For filling and frosting:
• Beat whipping cream and sugar in large bowl until peaks form. Add mascarpone to lemon curd in medium bowl; whisk until blended. Fold whipped cream into lemon-mascarpone mixture.
• Place 1 cake layer, flat side up, on platter. Brush with 1/4 of syrup. Spread 1/4 cup lemon curd over, then 1 cup lemon-mascarpone filling. Top with second cake layer; brush with 1/4 of syrup and spread with 1/4 cup lemon curd and 1 cup lemon-mascarpone filling. Repeat with third cake layer, syrup, lemon curd, and filling. Top with fourth cake layer. Brush with remaining syrup, then spread remaining lemon curd over. Spoon 2 cups lemon-mascarpone filling into pastry bag fitted with 1/4-inch star tip (to be used for rosettes). Spread remaining lemon-mascarpone filling as a frosting over sides of cake. Pipe small rosettes of frosting over top of cake, covering completely. Cover cake with cake dome; refrigerate at least 6 hours and up to 1 day.
• *Italian cream cheese available at Italian markets and many supermarkets.