Key Lime Layer Cake

4.65 from 17 reviews

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.

Prep Time1 30

Bake Time35

Chilling Time4

Total Time6 5

Servings:16 servings

Ingredients

1 recipe Vanilla Butter Cake
1 recipe Swiss Meringue Buttercream (or your favorite buttercream)
1 recipe Simple Syrup (flavored with 2 oz cup dark rum)
1 ¾ cups Lime Curd (with gelatin)

Cheesecake Layer

8 oz graham cracker crumbs (1 ½cups)
2 oz granulated sugar (¼ cup)
½ teaspoon ground cinnamon
3 oz unsalted butter (melted)
8 oz cream cheese (room temperature)
4 oz granulated sugar (½ cup)
1 lime
3 oz sour cream (⅓ cup, room temperature)
2 large eggs (room temperature)
1 teaspoon vanilla extract
Graham cracker crumbs for decoration

Instructions

Cake

Mix 1 recipe Vanilla Butter Cake according to the recipe and divide the batter between three 9”x3" 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.
Make 1 recipe Swiss Meringue Buttercream, 1 recipe Simple Syrup and 1 ¾ cups 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

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 8 oz graham cracker crumbs, 2 oz granulated sugar and ½ teaspoon ground cinnamon in a mixing bowl. Pour 3 oz unsalted butter (melted) over the crumbs and toss to combine. Dump the crumbs into the prepared pan and pat down to an even layer.
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.
In a large mixer bowl or stand mixer bowl, use the beater attachment to cream 8 oz 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.
Add 4 oz granulated sugar and the finely grated zest of 1 lime. Mix until no lumps of cream cheese remain. Scrape the bowl and paddle attachment again. Add 3 oz sour cream, scrape the bowl and paddle attachment again. With the mixer running on low speed, add 2 large eggs, one at a time. Scrape the bowl and paddle attachment between eggs. Add 1 teaspoon vanilla extract and the juice from the lime and mix until combined.
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.
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.
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

Fill a piping bag fitted with a star tip with buttercream (or use a disposable bag with the tip cut).
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.
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.
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.
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.

Nutrition