If you love citrus desserts, you are going to love today’s Key Lime Cake with White Chocolate Buttercream. It’s a nod to the classic key lime pie with key lime curd sandwiched between layers of key lime cake. All topped with a white chocolate buttercream that is the perfect complement to the lime flavor.
In an attempt to make a boxed white cake mix taste homemade I added homemade buttermilk (whole milk mixed with vinegar) along with key lime juice and lime zest to the batter. Well, I forgot the fundamentals of baking science and the result of all that acidity was two cake layers that were dense and barely rose. On my second attempt I decided to keep it simple and ended up with perfect cake layers.
While the cake layers themselves have just a hint of lime flavor the real star of the cake is the key lime curd. The flavor is spot on without being overpowering. As a heads up, the recipe for the curd will yield more than what’s needed for the cake. I ended up mixing my leftover curd with yogurt. You could do as I did, or top it on pancakes or waffles, or just enjoy it on its own since it’s so good! And to top it all off I made a white chocolate buttercream by beating melted white chocolate along with butter and a few other ingredients.
Two quick things to note regarding the key lime juice and white chocolate. For the key lime juice, I opted to use Nellie & Joe’s Key West Lime Juice. It’s become my go-to for whenever I make any key lime desserts. Now, if you are up to it and are able to find them you can squeeze fresh key limes to get the juice. Just keep in mind that key limes are smaller than regular limes and you will need a decent amount of them to get the amount of juice needed for the cake. As for the white chocolate, you may be tempted to use white chocolate chips as opposed to baking bars, but speaking from experience the bars are better as they melt smoothly. Which is important when making the buttercream. I used chips once to make white chocolate buttercream and the chips didn’t melt smoothly and my buttercream ended up with small chunks of white chocolate. The buttercream tasted good, but it was an unexpected texture. I used Ghirardelli white chocolate bars which can be found in the baking aisle, but you could also use Lindt white chocolate bars which can be found in the candy aisle.
Key Lime Cake with White Chocolate Buttercream
Ingredients:
For the Key Lime Curd:
1 cup sugar
Zest from 1 lime
6 egg yolks
1/2 cup key lime juice
1 stick unsalted butter, cubed
For the Key Lime Cake:
1 15.25oz. box white cake mix
3 eggs
1 cup water
1/2 cup vegetable oil
1/4 cup key lime juice
Zest from 2 limes
For the White Chocolate Buttercream:
2 4oz. white chocolate baking bars, chopped*
2 1/2 sticks (1 1/4 cup) unsalted butter, at room temperature
2 1/2 cup confectioners’ sugar
1 teaspoon vanilla extract
1/4 teaspoon salt
1/4 cup heavy whipping cream
Graham cracker crumbs to decorate, optional
*I used 2 4oz. Ghirardelli White Chocolate Baking Bars
Directions:
For the Key Lime Curd:
In a medium saucepan lightly whisk the egg yolks. Add the sugar and lime zest and continue whisking until well combined. Gradually whisk in the lime juice.
Heat over low heat and continue whisking the mixture until it begins to thicken and coats the back of a spoon.
Remove from the heat and whisk in the cubed butter. Continue whisking until the butter has melted.
Strain the curd through a fine mesh sieve into a food-storage container. Place a piece of plastic wrap directly on the surface of the curd (to prevent it from forming a skin) and allow to cool for a few minutes before covering and refrigerating for at least 8 hours. The curd will continue to thicken as it chills.
For the Key Lime Cake:
Preheat the oven to 350 F. Spray 2-8inch round cake pans with baking spray and set aside.
In a large bowl combine all the ingredients for the cake and beat with a hand mixer on medium speed until combined, careful not to overbeat. Divide the batter among the prepared pans – about 2 cups each – and bake in the preheated oven for 28-33 minutes, until a cake tester inserted in the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes before removing and transferring to a wire rack to cool completely. If you are not assembling the cake the same day as baking the cake rounds, wrap them in plastic wrap and refrigerate until ready to use.
For the White Chocolate Buttercream:
Place the chopped white chocolate in a microwave safe bowl and heat in the microwave for 30 seconds, stir and then continue to heat for 15 second intervals, stirring between each, until the chocolate is melted and smooth. Do not overheat as this will scorch the chocolate. Allow the chocolate to cool for 20 minutes.
In the bowl of a stand mixer beat the butter on medium speed until creamy. Gradually add in the cooled chocolate and continue beating until smooth. With the mixer on medium-low speed gradually add in the confectioners’ sugar. Beat in the vanilla extract and salt until combined.
Add in the heavy whipping cream and beat for a few seconds until incorporated and then increase the speed to high for 30-60 seconds to fluff the frosting.
To assemble the cake:
If necessary, level the cakes. Place one of the cakes on a cake board or a cake stand. Transfer some of the frosting to a piping bag (or resealable bag) and pipe a thick dam around the edge of the cake. Fill with the lime curd and then place the second cake on top. Crumb coat the cake and place in the refrigerator for 15 minutes. Frost the cake with the remaining frosting. If desired pipe swirls on top of the cake. If using, press the graham cracker crumbs on top of the cake and on the sides.
Recipe first appeared on Bead Yarn & Spatula
Bead Yarn & Spatula 