Lemon Layer Cake

Arrange racks in upper and lower thirds of oven; preheat to 350°. Line the bottoms of 2 (8") round pans with parchment, then grease with cooking spray.

In a medium bowl, whisk flour, cornstarch, baking powder, and salt.

In a large bowl, using a handheld mixer on medium-high speed (or in the large bowl of a stand mixer fitted with the whisk attachment), beat butter, granulated sugar, lemon zest and vanilla until light and fluffy. Add half of dry ingredients and beat on medium-low speed until just combined, then pour in buttermilk and beat until incorporated. Add remaining dry ingredients and stir with a wooden spoon until just combined.

In another large bowl, using handheld mixer on medium-high speed, beat egg whites until stiff peaks form. Add about one-quarter of whipped egg whites to batter and gently fold with a rubber spatula. Add remaining egg whites and fold until just combined. Divide batter between prepared pans.

Bake cakes until a tester inserted into the centers comes out clean, about 35 minutes. Transfer to a wire rack. Let cool in pans for 10 minutes. Run a knife around edges of pans, then carefully invert cakes onto rack and let cool completely.

In a large bowl, using handheld mixer on medium-high speed, beat cream cheese and butter until combined and smooth. Add confectioners' sugar and beat until smooth, then beat in vanilla and lemon juice.

Transfer one cake to a platter. Spread top with about one-third of frosting, then spread a thin layer of lemon curd over frosting. (Don't spread curd all the way to the edges, or it'll be messy to frost the sides later!)

Place a second cake layer on top, then cover entire cake with remaining frosting. Garnish top of cake with lemon zest.