Key Lime Cake with Key Lime Curd and Coconut Buttercream

This was, without exaggeration, the most time‑consuming cake I’ve ever made. Not because the recipe itself was wildly complex (although making homemade key lime curd certainly demanded some patience, and hunting down actual key limes felt like a small quest.) The real indulgence was this decadent, green‑tinted key lime coconut cake I wanted to make for a friend.

But the true time sink? The catastrophe that unfolded in my fridge.

The entire fully assembled cake (layers, filling, and a gloriously messy coconut buttercream) slipped, toppled, and collapsed inside the refrigerator. I cannot overstate the chaos of cleaning coconut buttercream and key lime curd from every surface. The entire fridge. Every shelf. Every drawer. It was absurd.

And the worst part is that I saw it coming. I knew I hadn’t given the cake enough chill time between stacking the layers, adding the curd, and trying to frost the outside. Cakes demand patience and multiple rounds of chilling, and I was simply too eager to get it done.

Still, I managed a pretty brilliant recovery. After scraping together the frosting and curd that had survived the fall, I reassembled the four layers and drove a wooden dowel straight through the center to keep everything in place. That alone felt like a small engineering triumph. Then I applied a thin crumb coat—a mix of icing and curd—to lock in the moisture and stabilize the structure, and let it chill for several hours.

Only after that did I finish it with a lush layer of coconut buttercream, a strawberry rosette on top, and a scattering of toasted shredded coconut.

And honestly? After all that drama, the cake turned out to be amazing. I’m so pleased, as this was a gift for my truly amazing friend, partner in crime, and woman who knows far too much about me that I may have to kill her for knowing too many of my secrets 😂🤣😂🤣😂🤣😂!!

Thank you, Valerie. 💖

Key Lime Cake with Key Lime Curd and Coconut Buttercream

Key Lime Cake:

1 cup melted butter
3 large eggs, room temperature
1 1/3 cup whole milk
1 cup sour cream
2 Tbs. fresh key lime zest
2 Tbs. fresh key lime juice
2 cups all-purpose flour
2 cups granulated sugar
½ cup powdered sugar
1 tsp. baking powder
1 tsp. baking soda
1 tsp. kosher salt
1 Tbs. whole milk coconut milk
1 Tbs. green food coloring
1 tsp. coconut extract

Beat together the butter, eggs, milk, sour cream (for moisture), and lime zest and juice, until smooth and creamy.

Add the flour and sugar, slowly, using a stand mixer. Once beginning to thicken, add the baking powder, baking soda, and salt.

Drizzle in the coconut milk, food coloring, and coconut extract, and mix until well combined.

Preheat the oven to 350°F.

Grease four 6” cake pans with butter or oil and line with parchment paper.

Divide the cake mix evenly into the four pans.

Bake for 20-25 minutes, until a toothpick inserted comes out clean.

Remove from the oven and cool for 30 minutes.

Slide a knife around the sides of the cooled cakes and release from pans, inverting onto parchment, and allowing to cool completely before wrapping in plastic wrap and chilling overnight in the fridge.

Key Lime Curd:

½ cup key lime juice
¾ cup granulated sugar
¼ cup butter, room temperature
2 large eggs
1 Tbs. green food coloring.

Combine the fresh key lime juice, sugar, and butter in a small pot over low heat on the stove. Stir rapidly until the sugar has dissolved and the mixture becomes super thick.
Remove from heat.
Beat together the eggs and temper with 2-3 Tbs. of the warm key lime mixture, whisking together constantly. Add another 2-3 Tbs. of the lime mixture, continually whisking with the eggs.
Finally, pour the tempered egg mixture into the sugared lime mixture and continue stir over very low heat, adding the food coloring, until the potion thickens by double and sticks to the back of a spatula.

Transfer to a small bowl and let cool on the counter or in the fridge overnight.

Coconut Buttercream:

1 cup butter, room temperature
1 cup shortening, room temperature
½ cup sweetened condensed coconut milk
4 cups powdered sugar
1 tsp. coconut extract

Using a stand mixer, cream together the butter and shortening until smooth and creamy. Add the condensed coconut milk and coconut extract and beat until well combined.

Add the powdered sugar, ½ cup at a time, and beat until the mixture is thick and creamy.

Topping:

strawberries cut into rosettes
shredded coconut flakes

Assembly:

Patience is KEY!!!!

Remove the cake layers from the fridge to prepare to frost.

Place the first layer on a 6” cake board and cake swivel tray, securing with a dash of buttercream.

Top with a layer of buttercream and then another layer of key lime curd. Repeat until the 4^th cake layer (top) has been added. Using any extra curd as a touch of homemade icing, gently cover the outside of the cake layers to seal in the moisture. BE SURE TO SECURE the layers by stabbing the center with a wooden kabob skewer or dowel.

Chill for several hours (DO NOT SKIP THIS STEP).

Once chilled and set, frost with the remaining combination of key lime curd and coconut buttercream until smooth and beautiful.

Top with a strawberry rosette and shredded coconut.

Store in the fridge before slicing and serving