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Key Lime Layer Cake

Key Lime Layer Cake has all the best things about Key Lime pie, in a cake. Buttery vanilla cake is layered with key lime curd, key lime cheesecake and a special graham cracker crunch. A hint of rum takes the flavor up a notch.

Right off the bat I’ll admit that this is not a “super quick and easy” recipe. None of the components are difficult to make, but it is a bit of a project that is best accomplished over a couple of days.

I wanted to create a special layer cake that had the wonderful flavors of Key Lime Pie. But I did go off script a bit because I couldn’t resist adding a cheesecake layer. Even better, there’s a special graham cracker crunch that is the star of this cake.

Yes, yes, I know I don’t actually use “key limes” in the recipe. But since everyone refers to any lime dessert as “key lime”, I’ve taken the liberty to name this cake after the famous pie. If you have key limes you can certainly use them.

Scroll through the step by step photos to see how to make This Cake:

four photos showing steps to make, bake and release a cheesecake layer with graham cracker crust.
1. Pour the lime cheesecake batter over the graham cracker crust. 2. Bake the layer in a water bath. 3. Remove the pan from the freezer and use a blowtorch or hot water to release the cake from the pan. 4. Keep the layer frozen until you assemble the cake.
four photos showing how to build a key lime layer cake
1. Brush the first cake layer with rum syrup. 2. Spread a thin layer of buttercream, then place the cheesecake layer with the graham crust down. Top with more buttercream and another cake layer. 3. Pipe a buttercream dam to hold in the lime curd. 4. Spread lime curd inside the buttercream dam.
four photos showing how to ice and finish a key lime layer cake.
1. Place the last layer on top of the lime curd and brush with rum syrup. 2. Crumb coat the cake and refrigerate to firm up the buttercream. 3. Ice the cake with a final coating of buttercream. 4. Pipe a buttercream border and fill in with more lime curd.

How to work ahead to make this cake:

  • The cheesecake layer must be frozen so it has to be made at least a day before assembling the cake. You can make and freeze the cheesecake several days or even several weeks before you’re ready to put the cake together.
  • The lime curd can be made ahead and refrigerated for 2-3 days or frozen for up to 3 months.
  • The rum syrup can be made up to a week ahead and refrigerated.
  • The cake layers can be made ahead and stored at room temperature for 1 day or frozen for up to 3 months.
  • The Swiss Meringue Buttercream can be refrigerated for 2-3 days or frozen for up to a month. Bring the buttercream back to room temperature and re-whip before using.
  • The assembled cake should be refrigerated until an hour before serving, or as long as 3-4 hours ahead if the room is not very warm. You want the cake to soften a bit before serving for the best flavor.

Since you love lime, here are some other recipes you should try:

Layer cakes don’t have to be just cake and frosting. Here are a few more innovative layer cakes:

If you love this recipe as much as I do, I’d really appreciate a 5-star review.

Key Lime Layer Cake

Key Lime Layer Cake

Yield: 12-16 servings
Prep Time: 1 hour 30 minutes
Bake Time: 35 minutes
Chilling Time: 4 hours
Total Time: 6 hours 5 minutes

Key Lime Layer Cake has all the best things about Key Lime pie, in a cake. Buttery vanilla cake is layered with key lime cheesecake, graham cracker crunch and key lime curd. A hint of rum takes the flavor up a notch.

Ingredients

Cheesecake Layer

  • 6 tablespoons (3 oz, 84g) unsalted butter, melted
  • 1 1/2 cups (8 oz, 224g) graham cracker crumbs (about 13 crackers)
  • 1/4 cup (2 oz, 56g) granulated sugar
  • 1/2 teaspoon ground cinnamon
  • 1 cup (8oz, 224g) cream cheese, room temperature
  • 1/2 cup (4 oz, 112g) granulated sugar
  • Finely grated zest from 1 large lime
  • 1/3 cup (3 oz, 85g) sour cream, room temperature
  • 2 large eggs, room temperature
  • 1 tablespoon fresh lime juice
  • 1 teaspoon vanilla extract
  • Graham cracker crumbs for decoration

Instructions

Cake

  1. Mix the cake according to the recipe and divide the batter between three 9” pans lined with a parchment round or buttered and floured. Bake as instructed in the recipe. If you only have 2 pans, bake 1/3 of the batter in one pan and 2/3 of the batter in the other pan. Split the thicker cake into 2 layers so you have a total of 3 layers. Trim the brown tops from the layers as this can make the cake layers separate later.
  2. Make the buttercream, simple syrup and lime curd according to the recipe. Each component can be made several days ahead. Refrigerate the buttercream and lime curd for up to 2 days. Bring the buttercream to room temperature and rewhip before assembling the cake.

Cheesecake Layer

  1. Preheat the oven to 350°F. Line an 8"" pan with parchment paper. If you only have a 9" pan you can bake it in that but you will need to trim the sides of the cake later. Don't skip the parchment liner or it will be almost impossible to handle the cheesecake layer. Combine the graham cracker crumbs, sugar and cinnamon in a mixing bowl. Pour the melted butter over the crumbs and toss to combine. Dump the crumbs into the prepared pan and pat down to an even layer.
  2. Bake the crust about 10 minutes until fragrant and just beginning to brown. Remove from the oven and set aside to cool. Leave the oven on.
  3. In a large mixer bowl or stand mixer bowl, use the beater attachment to cream the cream cheese until soft and smooth. You're not trying to add air, just soften the cream cheese. Keep the mixer on low speed. Scrape the bowl and the beater.
  4. Add the granulated sugar and lime zest, mix until no lumps of cream cheese remain. Scrape the bowl and paddle attachment again. Add the sour cream, scrape the bowl and paddle attachment again. With the mixer running on low speed, add the eggs one at a time. Scrape the bowl and paddle attachment between eggs. Add the vanilla and lime juice and mix until combined.
  5. Pour the batter into the pan with the graham cracker crust. Set the pan onto a rimmed baking sheet or any pan that is at least 3" larger than the cake pan. I use a 12" skillet. Set the baking sheet on the middle rack of the oven and pour 1" of water into the baking sheet. Bake until the center of the cheesecake is set, about 20 minutes.
  6. Allow the cheesecake to cool to room temperature then place the pan in the freezer several hours or overnight. The layer should be frozen solid. If you are working more than a day ahead, wrap the pan to avoid freezer burn.
  7. To remove the cheesecake from the pan dip the bottom of the pan in a bowl of very hot water, run a knife or spatula around the sides of the cake and flip it out onto a flat plate. Alternately, you can flip the pan over and run a propane torch across the bottom of the pan. Remove the parchment round from the bottom and flip right side up. If not assembling the cake immediately, wrap the cheesecake layer and freeze until ready to use.

Assembly

  1. Fill a piping bag fitted with a star tip with buttercream (or use a disposable bag with the tip cut).
  2. Set one layer of the cake, flat side down, onto a cardboard cake round or a serving plate. Brush the layer generously with the rum syrup. Spread a 1/4" thick layer of buttercream over the layer. (If you have a 9" cheesecake layer, trim 1/2" from around the sides of the cake so the cheesecake layer is slightly smaller than the cake layers.) Place the cheesecake layer, with the graham cracker crust at the bottom, onto the buttercream. Spread another 1/4" thick layer of buttercream over the cheesecake.
  3. Place the second cake layer onto the cake. Brush the layer with syrup and pipe a dam of buttercream around the rim of the layer. If your lime curd is very stiff from being chilled, microwave briefly to soften it until it's spreadable. Set aside a 1/2 cup of the lime curd and scoop the rest onto the layer. Smooth the curd until even.
  4. Place the 3rd cake layer, brush with syrup. Ice the cake with a thin crumb coat of buttercream. Refrigerate the cake for about 20 minutes to set the crumb coat. Ice the cake with a final coating of buttercream.
  5. Coat the sides of the iced cake with graham cracker crumbs. Use a piping bag fitted with a star tip to pipe a border around the top of the cake. Spread the last 1/2 cup of curd within the border. Refrigerate until 1-2 hours before serving.

Notes

The cake must be stored in the refrigerator because of the cheesecake and curd fillings. Take the cake out 1-4 hours (depending on the temperature of the room) before serving to allow it to soften. Leftovers can be refrigerated and the cake freezes very well.

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