Lemony Petit Fours

Preheat oven to 350°F. Gather all ingredients. Line a 13 x 9–inch quarter sheet pan with parchment paper.

To prepare cake, combine flour, baking powder, salt, and baking soda in a medium bowl, stirring with a whisk. Place butter and granulated sugar in a large bowl; beat with an electric mixer at medium speed until light and fluffy, 3 to 4 minutes, scraping sides of bowl occasionally. Beat in eggs, 1 at a time, beating well after each addition. Add extracts and beat until just combined. With mixer on low speed, add flour mixture and buttermilk alternately to butter mixture, beginning and ending with flour mixture.

Spread batter (it will be thick) into prepared pan, smoothing with an offset spatula. Bake at 350°F until a wooden pick inserted in center comes out clean, 22 to 25 minutes.

Cool cake in pan on a wire rack for 10 minutes. Using 2 spatulas to support cake, lift cake (still on parchment) out of pan and place on a wire rack to cool completely, 35 to 45 minutes.

Place another cooling rack or a thin, flexible cutting board on top of cake; invert cake and carefully remove parchment paper. Turn cake back over. Using a long serrated knife, carefully split cake horizontally into 2 layers. Using 2 spatulas, carefully lift off top cake layer. Stir together lemon curd and lemon zest; spread evenly over bottom cake layer. Carefully replace top cake layer over lemon curd.

To prepare buttercream, place butter in a medium bowl; beat with an electric mixer at medium-low speed until smooth and creamy. With mixer on low speed, gradually add 1 cup powdered sugar, beating until smooth. Beat in extracts, then beat in buttermilk. Add remaining 1/4 cup powdered sugar and beat on medium speed until smooth and creamy. Spread buttercream evenly over top of cake. Place cake in freezer for 1 hour.

To prepare glaze, fill a large saucepan half full with water and bring to a simmer. Combine 6 cups powdered sugar, hot water, corn syrup, vanilla, salt, and almond extract in a large heatproof bowl, stirring with a whisk until smooth. Scoop out 1/3 cup of glaze into a small bowl; stir in remaining 2 tablespoons powdered sugar and set aside. Add food coloring to large bowl of glaze, if desired, 1 drop at a time until desired color is achieved. Place bowl over simmering water and heat glaze to a temperature of 90 to 95°F. Maintain glaze at this temperature.

Remove cake from freezer. Using a large, straight-sided knife (such as a chef’s knife), trim off all four sides of cake to form an even, precise rectangle. Cut cake into 1 1/4- to 1 1/2-inch squares.

Cover a large area of countertop with parchment or wax paper, if desired, for easy cleanup. Arrange 2 cooling racks on top of paper. Either gather 2 plastic forks or 2 regular forks. If using plastic forks, break off the middle 2 tines of one of the forks. Bring cake squares and glaze near the cooling racks. Place 1 cake square on top of the fork with the broken-out tines or onto a regular fork. Hold cake square over bowl of glaze and, using a small ladle or a serving spoon, ladle glaze all over cake square, making sure to coat all sides. Allow excess glaze to drip off cake square into bowl, then scrape fork over side of bowl to remove any remaining excess. Using the other fork, carefully push glazed cake square onto a cooling rack. Repeat process with remaining cake squares and glaze, spacing apart on cooling racks to allow for even drying. If glaze gets too thick, rewarm over simmering water to 90°F to 95°F.

Allow glazed cake squares to set for 30 minutes. Meanwhile, scrape reserved white glaze into a small zip-top plastic bag. Snip off a tiny hole from 1 bottom corner of bag. Drizzle white glaze over cake squares. Allow petit fours to stand until glaze is fully set, at least an additional 1 1/2 hours or up to 6 hours.