Raspberry-Lemon Cakelets

Preheat oven to 325°. Lightly brush the bottom of an 18x13-inch baking pan with softened butter. Line with parchment paper. Brush softened butter over the paper and sides of the pan. Dust with all-purpose flour; tap out excess.

Place granulated sugar, lemon zest and salt in a food processor; process 1 minute.

In a large bowl, whisk together cake flour and baking powder. In a glass measuring cup, whisk together buttermilk, egg whites, the whole egg, 2 tablespoons lemon juice and the vanilla.

In a stand mixer fitted with the paddle attachment, beat unsalted butter on medium speed until fluffy, about 2 minutes. Add the processed lemon sugar; beat until fluffy, about 2 minutes. On low speed, beat in about one-third of the flour mixture, followed by half of the buttermilk mixture. Repeat, ending with the final one-third of the flour mixture. Increase speed to high; beat batter until light and fluffy, about 1 minute.

Scrape batter into prepared pan. Spread evenly. Bake until cake turns barely golden, is springy to the touch and pulls away from the sides of pan (20 to 22 minutes). Cool completely in pan. Turn cake out onto a large cutting board or work surface; discard paper.

Slice cake into thirds the short way. Spread two portions with a thin layer of preserves. Stack the layers, ending with the plain portion. Slide cake onto an unrimmed baking sheet and chill 1 hour. Remove from refrigerator; cut into 10 rectangles. Place cakes on a wire rack set over wax paper.

In a medium bowl, whisk together powdered sugar and 3 to 4 tablespoons of the remaining lemon juice to form a glaze of drizzling consistency. Drizzle over cakes. If you like, decorate with edible flowers.