Coconut Lime Layer Cake with Zesty Lime Frosting

FOR THE CAKE:

• 5 large egg whites
• 1 1/2 cups (360 g) canned unsweetened coconut milk, divided
• 1 tablespoon coconut flavoring
• 3 cups (340 g) cake flour
• 2 1/3 cups (470 g) granulated sugar
• 4 1/2 teaspoons baking powder
• 1/2 teaspoon salt
• 1 cup (226 g) unsalted butter, softened

LIME CURD FILLING:

• 1/2 cup (112 g) fresh lime juice
• Zest of 2 limes
• 1/2 cup (100 g) granulated sugar
• 5 large egg yolks
• 1/4 cup (56 g) unsalted butter
• Food coloring, optional

COCONUT-LIME BUTTERCREAM:

• 5 large egg whites
• 1 1/4 cups (250 g) granulated sugar
• 2 cups (450 g) unsalted butter, room temperature
• 1/4 cup coconut milk or cream of coconut
• Zest of 2 limes
• 1 teaspoon coconut extract
• Approximately 1 cup toasted coconut, sweetened or unsweetened

TO MAKE THE CAKE:

• Preheat oven to 350°F. Butter and flour two or three 8-inch or 9-inch cake pans and line with parchment paper.
• Whisk together the egg whites, 1/2 cup coconut milk, and coconut flavoring.
• In a stand mixer bowl with the paddle attachment, combine flour, sugar, baking powder, and salt. Add butter and the remaining 1 cup coconut milk on low until moistened. Increase to medium and beat until light and fluffy, about 2 minutes.
• Add the egg white mixture in three additions, mixing just until incorporated.
• Divide batter among prepared pans and bake 35–40 minutes, or until a toothpick comes out clean. Cool in pans 10 minutes, then transfer to racks to cool completely.
• Layers can be wrapped and refrigerated up to 4 days or frozen for longer storage; defrost before assembling.

TO MAKE THE LIME CURD:

• Combine lime juice, zest, and sugar in a small saucepan over medium heat until sugar dissolves.
• Whisk egg yolks in a bowl, then slowly whisk in the hot lime mixture in a steady stream until combined.
• Return to the saucepan and cook over medium heat, stirring constantly, until thickened and coating the back of a spoon, about 4–5 minutes. Stir in butter.
• Pass curd through a mesh strainer to remove zest and any cooked egg bits. Chill completely before using. Add a small amount of food coloring if you prefer a green color.

TO MAKE THE COCONUT-LIME BUTTERCREAM:

• Combine egg whites and sugar in a heatproof bowl and place over simmering water, ensuring the bowl bottom does not touch the water.
• Stir frequently until sugar is dissolved and mixture reaches 160°F (or is hot to the touch).
• Transfer to a stand mixer and whisk on high until cooled and medium peaks form, about 5 minutes.
• With the mixer on medium, add butter a tablespoon at a time. The mixture may look soupy at first but will thicken once all the butter is added. If it separates, chill 15 minutes and whip again.
• Stir in coconut milk or cream, lime zest, and coconut extract, then beat until light and fluffy.

TO ASSEMBLE CAKE:

• Mix about 1 cup of buttercream into the chilled lime curd until smooth.
• Level or split cake layers as desired, then place one layer on a cake stand or plate.
• Pipe a small buttercream dam around the edge, fill the center with 1/2–1/3 of the lime curd mixture (depending on layers), and top with the next layer. Repeat for remaining layers.
• Frost the outside of the cake with buttercream, decorate with toasted coconut and lime slices, and chill at least 30 minutes before serving.
• Store leftovers in the refrigerator for up to 4 days.

• You can bake this cake in 8- or 9-inch pans. Two pans give a double layer, three pans give a triple layer. If batter overflows your pans, use additional pans or larger-diameter pans. Deeper pans hold more batter.
• Lime curd is naturally yellow; add a tiny amount of gel food coloring if you want a green hue. Start with a small amount and adjust carefully.
• To toast coconut, spread it in a single layer on a sheet pan and bake at 350°F for 3–5 minutes, watching closely so it doesn’t burn. Cool completely before using.
• For guidance on building and assembling layered cakes, consult a step-by-step cake assembly tutorial.