• Preheat oven to 350°.
• Line a 17¼×11½-inch baking pan with parchment paper. Spray with baking spray.
• In a large bowl, beat together butter and sugar with a mixer at high speed until light and fluffy, approximately 5 minutes.
• Add eggs, one at the time, beating well after each addition.
• Add extracts, beating until combined. Using a rubber spatula, scrape down sides and bottom of bowl.
• In a medium bowl, whisk together flour, baking powder, baking soda, and salt.
• Gradually add flour mixture to butter mixture in thirds, alternately with buttermilk, beginning and ending with flour mixture, beating until incorporated. Using an offset spatula, spread batter in an even layer into prepared pan.
• Tap pan gently on countertop to reduce air bubbles.
• Bake until cake edges are golden brown and a wooden pick inserted in center comes out clean, 15 to 17 minutes.
• Let cool completely in pan.
• Wrap cake securely with plastic wrap and freeze for 4 hours, or until cake is frozen.
• Using a 2-inch round cutter, cut 34 rounds from frozen cake.
• Let thaw completely. (Cover lightly with plastic wrap to prevent drying out.)
• Place Mascarpone Whipped Cream in a piping bag fitted with a medium round tip (Wilton #12).
• Pipe around edge of 17 cake rounds, and fill circle in an even layer.
• Top each with remaining 17 cake rounds.
• Place Lemon Buttercream in another piping bag fitted with a large open star tip (Wilton#1M).
• Pipe a rosette on tops of cakes.
• Garnish with coconut, if desired.
• Serve immediately, or place in a covered container and refrigerate.
• Let come to room temperature before serving.

Mascarpone Whipped Cream:

• In a medium bowl, beat together cream, confectioners’ sugar, and vanilla extract with mixer at high speed until light and fluffy.
• Add mascarpone cheese, beating until incorporated.
• Use immediately.

Lemon Buttercream:

• In a large bowl, beat together butter, confectioners’ sugar, lemon juice, and salt with mixer at low speed until combined. Increase speed to high, beating until thick, smooth, and fluffy.
• Use immediately.