Preheat oven to 350 degrees. Grease and flour
3 (9-inch) round cake pans; set aside.
In a large bowl
, beat butter and sugar at medium speed with an electric mixer until fluffy. Add vanilla extract, beating to combine.
In a medium bowl, sift together flour, baking powder, and salt. Gradually add flour mixture to butter mixture, alternately with buttermilk, beginning and ending with flour mixture. Fold in egg whites, one-third at a time. Divide batter among prepared pans.
Bake for 20 minutes, or until a wooden pick inserted in center comes out clean. Let cool in pans for 10 minutes. Remove cake layers from pans and cool completely on wire racks.
Spread Strawberry Curd evenly between cake layers. Spread Strawberry Frosting on sides and top of cake. Garnish with fresh strawberries, if desired.
In the work bowl of a food processor
or the container of a blender
, process strawberries until smooth. Reserve 1/2 cup
strawberry puree for Strawberry Frosting.
In a heavy saucepan, combine sugar and cornstarch. Add strawberry puree, lemon juice, and egg yolks. Cook over medium heat for 7 to 8 minutes, or until very thick, whisking constantly.
Remove from heat; gradually add butter, whisking until melted. Add strawberry extract, stirring to combine. Cool mixture slightly; cover and refrigerate for 2 hours.
In a large bowl, beat butter and cream cheese at medium speed with an electric mixer until smooth. Add strawberry puree and strawberry extract, beating until combined. Gradually add confectioners' sugar, beating until a smooth and spreadable consistency is reached.