Island Breeze Coconut Lime Cake

FOR THE CAKE:

• ▢ 5 large egg whites
• ▢ 1 ½ cup (360 grams) canned unsweetened coconut milk , divided
• ▢ 1 tablespoon coconut flavoring
• ▢ 3 cups (340 grams) cake flour
• ▢ 2 ⅓ cups (470 grams) granulated sugar
• ▢ 4 ½ teaspoons baking powder
• ▢ ½ teaspoon salt
• ▢ 1 cup (226 grams) unsalted butter , softened to room temperature

LIME CURD FILLING:

• ▢ ½ cup (112 grams) fresh lime juice
• ▢ Zest of 2 limes
• ▢ ½ cup (100 grams) granulated sugar
• ▢ 5 large egg yolks
• ▢ ¼ cup (56 grams) unsalted butter
• ▢ Food coloring , optional (see Notes)

COCONUT-LIME BUTTERCREAM:

• ▢ 5 large egg whites
• ▢ 1 ¼ cups (250 grams) granulated sugar
• ▢ 2 cups (450 grams) unsalted butter , at room temperature
• ▢ ¼ 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 your oven to 350°F (175°C). Prepare two or three 8-inch or 9-inch cake pans by generously buttering and flouring them, then lining the bottoms with parchment paper. This step ensures easy release of your cake layers. (See Notes for pan size guidance).
• In a small, separate bowl, whisk together the egg whites, ½ cup of the unsweetened coconut milk, and the coconut flavoring until well combined. Set this liquid mixture aside.
• In the bowl of a stand mixer fitted with a paddle attachment, combine the cake flour, granulated sugar, baking powder, and salt. Add the softened butter and the remaining 1 cup of coconut milk. Begin mixing on low speed until the dry ingredients are just moistened. Increase the speed to medium and beat for approximately 2 minutes until the mixture is light, pale, and fluffy, making sure to scrape down the sides of the bowl as needed to ensure everything is well incorporated.
• Gradually add the reserved egg white mixture in three equal additions, mixing just long enough after each addition to incorporate it into the batter. Be careful not to overmix, as this can lead to a tough cake. Scrape down the sides of the bowl between additions to ensure an even batter.
• Divide the prepared cake batter evenly among your buttered and floured pans. Bake for 35-40 minutes, or until a wooden toothpick inserted into the center of a cake comes out clean. Allow the baked cakes to cool in their pans for about 10 minutes before carefully inverting them onto wire racks to cool completely.
• For convenience, cake layers can be prepared in advance. Once completely cooled, wrap each layer tightly in plastic wrap and store them in the refrigerator for up to 4 days, or freeze them for several months. Always ensure they are defrosted completely before you begin the assembly process.

TO MAKE THE LIME CURD:

• In a small saucepan, combine the fresh lime juice, lime zest, and granulated sugar. Place the saucepan over medium heat and cook, stirring occasionally, until the sugar has completely dissolved. This step ensures a smooth curd.
• Place the large egg yolks in a medium-sized bowl. While continuously whisking, slowly stream the heated lime juice mixture into the egg yolks in a thin, steady stream. This tempering process prevents the eggs from scrambling. Continue whisking until the mixture is thoroughly combined.
• Return the tempered mixture to the saucepan. Cook over medium heat, stirring constantly, for 4-5 minutes, until the curd visibly thickens. It should be thick enough to coat the back of a spoon. Remove from heat and stir in the unsalted butter until it is completely melted and incorporated, giving the curd a glossy finish.
• For a perfectly smooth curd, pass it through a fine-mesh strainer to remove any bits of zest or cooked egg particles. If desired, stir in a tiny drop of green food coloring for a more vibrant hue (see Notes). Chill the lime curd completely in the refrigerator before using; it will thicken further as it cools.

TO MAKE THE COCONUT-LIME BUTTERCREAM:

• In the clean bowl of your stand mixer, combine the egg whites and granulated sugar. Place this bowl over a pot of simmering water, ensuring the bottom of the bowl does not touch the water. This creates a double boiler effect.
• Heat the egg mixture, stirring frequently with a whisk, until all the sugar crystals have completely dissolved and the mixture feels hot to the touch. For the most precise results and safety, use a candy thermometer to heat the mixture to 160°F (71°C).
• Carefully transfer the bowl from the simmering water back to the stand mixer. Attach the whisk attachment and beat the egg white mixture on high speed until it has cooled down significantly and the egg whites form firm, glossy medium peaks. This usually takes about 5 minutes, depending on your mixer.
• Reduce the mixer speed to medium and begin adding the room-temperature unsalted butter, one tablespoon at a time. The mixture may initially deflate and appear somewhat soupy or curdled; this is normal. Continue beating. Once all the butter has been incorporated, the buttercream will begin to thicken and come together into a smooth, luscious frosting. If it still appears too thin, chill the entire bowl in the refrigerator for 15 minutes, then whip again until it reaches the desired consistency.
• Finally, stir in the coconut milk or cream of coconut, lime zest, and coconut extract. Beat the buttercream on medium-high speed until it becomes incredibly light, fluffy, and perfectly combined.

TO ASSEMBLE CAKE:

• To lighten the lime curd for easier spreading and a balanced flavor, add about 1 cup of the prepared coconut-lime buttercream to the chilled lime curd. Stir gently until the two are smoothly combined.
• If your cake layers have domed tops, level them off using a serrated knife for even stacking. You may also split your cake layers in half horizontally to create more thin layers, if desired (for a full guide, see our tutorial on cutting even cake layers). Place your first cake layer onto a serving plate or cake stand.
• Using a piping bag or an offset spatula, create a small “dam” or border of plain buttercream around the very edge of the cake layer. This barrier is crucial for preventing the lime curd filling from leaking out. Spoon and spread about ½ or ⅓ of the lime curd mixture (adjusting based on the total number of layers you have) evenly into the center of the cake layer, staying within the buttercream dam. Carefully place the next cake layer on top.
• Repeat the dam-and-fill process with the remaining cake layers and lime curd mixture, stacking them neatly.
• Once all layers are stacked, use the remaining buttercream to frost the entire cake, covering the top and sides smoothly. Decorate your cake as desired, perhaps with additional buttercream swirls or fresh lime slices. Finish by topping the cake with a generous amount of toasted coconut for an enhanced tropical flavor and visual appeal.
• For the best results and to allow the flavors to meld beautifully, store the assembled cake in the refrigerator for at least 30 minutes before slicing and serving. Any leftover cake can be stored in an airtight container in the fridge for up to 4 days.

• Choosing Your Cake Pans: This recipe is versatile and can be baked in either 8-inch or 9-inch cake pans. For a taller, more dramatic cake, I personally prefer using 8-inch pans. However, the choice is entirely yours and depends on the final look you’re aiming for. You can use two pans for a classic double-layer cake, or three pans for a more impressive triple-layer creation. For an even more elaborate presentation, you can bake in two pans and then slice each layer in half horizontally to create a stunning quadruple-layer cake. Please note that some comments indicate the batter might not fit into two standard 8-inch pans if they are only 2 inches deep. My pans are typically 4 inches deep and can accommodate more batter. If your pans are shallower, consider using three 8-inch pans or opting for 9-inch pans to prevent overflow.
• Vibrant Lime Curd Color: Fresh lime curd is naturally a beautiful pale yellow. If you desire a more striking green hue for your curd to emphasize the lime flavor, I recommend adding a tiny amount of blue gel food coloring. Start with a very small drop, as a little goes a long way, and you can always add more until you achieve your desired shade. Be aware that adding green food coloring can sometimes result in a bright, almost neon green color.
• How to Perfectly Toast Coconut: Toasted coconut adds an incredible depth of flavor and a lovely texture to your cake. To achieve this, spread your shredded coconut (sweetened or unsweetened, as per your preference) in a single, even layer on a baking sheet. Bake it in a preheated oven at 350°F (175°C) for approximately 3-5 minutes. It’s crucial to watch the coconut very closely during this time, as it can go from golden to burnt very quickly due to its natural oils. Remove it from the oven as soon as it turns light golden brown and allow it to cool completely before using.
• Assembling Your Layer Cake: For detailed visual guidance and comprehensive tips on successfully stacking and frosting your cake layers, refer to my complete tutorial on how to build a layer cake. This resource covers everything from leveling to crumb coating, ensuring a professional finish.

Parts of this recipe were thoughtfully inspired by the excellent Layered cookbook by Tessa Huff.