Key Lime Cake (A Doctored Cake Mix Recipe)

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This moist, delicious, and easy Key Lime Cake recipe starts with a cake mix! It has so much flavor and is perfect for spring and summer celebrations.  

In this recipe, Key Lime Cake layers are filled with a luscious key lime curd and whipped cream cheese frosting. A few added ingredients have transformed a simple white cake mix into a memorable key lime cake that is guaranteed to become a favorite. We just love light and flavorful cakes with fruit

Nobody would ever guess that this key lime layer cake begins with a simple cake mix.    

Key Lime Layer Cake- A Doctored Cake Mix Recipe

How to Make Key Lime Cake from a Cake Mix

  • Preheat the oven to 350 degrees F. Grease and flour three 8 inch round cake pans. (We like to line our pans with parchment paper also).  In the bowl of your mixer, add the white cake mix, flour, sugar, baking powder, salt and zest of 2 limes.

 

  • Whisk these dry ingredients for 30 seconds to combine.  Add the melted butter, egg whites, lime juice, milk and vegetable oil.

 

  • Mix the cake batter for one minute at medium speed, scrape the bottom and sides of the mixing bowl then mix one minute more.

 

  • Divide the batter between three prepared 8 inch round pans.  Bake for approximately 22 to 25 minutes or until a toothpick inserted into the center can be removed with just a few crumbs attached.  Allow the key lime cake layers to cool 5 to 10 minutes then turn out of pans. 

Key Lime Cake Recipe- Doctored Cake Mix

Can This Cake be Frozen?

Freezing cake layers is an optional step but one that I like to do whenever time allows. It doesn't matter if I'm making scratch cake layers or cake layers from a cake mix- We find that wrapping and freezing the cake layers while they are still warm adds a boost of moisture to cakes (and this key lime cake is already moist on it's own)! 

Another benefit of freezing is that it means that you can bake your cake layers well in advance- yay! In fact, cake layers that are tightly wrapped and frozen stay fresh for up to three months.

Finally, some bakers and cake decorators prefer to work with partially frozen cake layers when assembling their cakes because they are less fragile and can be easily handled. 

Notes on Wrapping and Freezing Cake Layers

For best results, freeze your cake layers individually and wrap them tightly in plastic wrap and then foil while they are still warm.

We allow the freshly baked cake layers to cool on a cooling rack still in their pans for about 10 minutes before flipping them out and wrapping. I like to place each layer on a foil-wrapped cake board before wrapping the and freezing for additional support. (Wrapping the cake boards in foil means that the boards can be unwrapped and re-used). 

To thaw the cake layers, simply place on the kitchen counter still wrapped until condensation droplets form on the foil. Then, unwrap and continue to thaw.

Key Lime Curd and Whipped Cream Cheese Frosting

The Key Lime cake layers have a nice, light lime flavor. We wanted to bring in additional lime flavor with the filling, and lime curd is a great choice!

We've made lime curd in the past for other cakes, and for today's recipe, we used Nellie & Joe's Key West Lime Juice as a substitute for freshly squeezed lime juice. It worked great and is delicious! However, you could also use freshly squeezed lime juice in the recipe as well!

 

In addition to the lime curd filling, we also added a wonderful, easy whipped cream cheese frosting between the cake layers and frosted the cake around the sides with it as well.

 

Whipped Cream Cheese Frosting is a combination of cream cheese frosting (a cream cheese and powdered sugar combination) with freshly whipped cream folded into it.

Whipped Cream Cheese Frosting

The consistency of the whipped cream cheese frosting is much like whipped cream although a bit more stable.

After spreading the top of the cake with the final layer of key lime curd, I frosted around the sides of the cake with whipped cream cheese frosting and added a rosette border around the top and shell border around the base using a 2D piping tip.

**This frosting is very soft- if you need to do much traveling with the cake, or if you are in a very hot climate, I would opt for a frosting that gets nice and firm when chilled so that it is easier to travel with.

 

Whipped Cream Cheese Frosting

 

 

 

 

Key Lime Layer Cake- Doctored Cake Mix

 

Other favorite Lime Cakes

If you love lime desserts, we have more cakes for you to try!

 

 

 

 

 

Also, don't miss our full roundup of the BEST Cakes for Spring and Summer! We have so many light and fruity cake recipes to share with you!

 

Moist Key Lime Layer Cake- Doctored Cake Mix Recipe

 

 

Key Lime Layer Cake- A Cake Mix Recipe

 

Key Lime Cake (A Doctored Cake Mix Recipe)

Key Lime Layer Cake on glass pedestal

We love this moist, refreshing Key Lime Layer Cake and it is so easy to make using a cake mix!

Ingredients

Key Lime Cake

  • 1 box (15.25) white cake mix ( we used Classic White Duncan Hines)
  • 1 cup (121g) all purpose flour (spoon into cup and level off)
  • 1 cup (200g) sugar
  • 1 teaspoon (5g) baking powder
  • ½ teaspoon (3g) salt
  • zest of 2 limes
  • 1 ½ sticks (12T)(179g) unsalted butter, melted
  • 4 egg whites (large eggs)
  • ¼ cup (55g) lime juice (We used Nellie & Joe's Key West Lime Juice)
  • 1 cup (242g) milk
  • 2 Tablespoons (16g) vegetable oil ( we use Canola oil)

Lime Curd Filling

  • ¾ cup (150g) sugar
  • ¼ cup (30g) cornstarch
  • 1 cup (242g) water
  • 2 egg yolks, slightly beaten
  • 2 Tablespoons (28g) unsalted butter
  • zest of 2 limes
  • ¼ cup (55g) lime juice (We used Nellie & Joe's Key West Lime Juice)

Whipped Cream Cheese Frosting

  • Two 8 ounce (423g total weight) packages cream cheese, softened. It must be full fat, not
  • reduced fat or cream cheese in a tub those are too soft.
  • 2 cups (230g) powdered sugar, sift then measure
  • 2 teaspoons (8g) vanilla extract
  • 3 cups (696g) heavy whipping cream

Instructions

Instructions for Cake

  1. Preheat the oven to 350 degrees.  Grease and flour three 8 inch round cake pans.  In the bowl of your mixer and the cake mix, flour, sugar, baking powder, salt and zest of 2 limes.  
  2. Whisk for 30 seconds to combine.  Add the melted butter, egg whites, lime juice, milk and oil.
  3. Mix 1 minute at medium speed, scrape the bottom and sides of the bowl then mix 1 minute more.
  4. Divide the batter between three prepared 8 inch round pans.  Bake for approximately 22 to 25 minutes.  Let cool 5 to 10 minutes then turn out of pans. 

Instructions for the Key Lime Curd

  1. In a saucepan, add the sugar, cornstarch and water.  Over medium heat, stir the mixture constantly until it thickens and comes to a boil.  Boil for 1 minute, remove from the heat.
  2. Spoon about ½ cup of the hot mixture into a small bowl containing the egg yolks and stir quickly until combined.
  3. Pour the egg mixture back into the saucepan.  Return pan to medium heat and cook, stirring constantly, approximately 2 minute.  Th mixture will thicken slightly.
  4. Remove from the heat and stir in the butter, lime juice and lime zest.  Cool before using.

Instructions for the Whipped Cream Cheese Frosting

  1. Freeze the mixing bowl and whisk attachment or beaters  15 minutes or move before whipping the cream ( 30 minutes if chilling in the refrigerator.
  2. Use the whisk attachment for a stand mixer, beaters on your hand mixer.  Beat the cream until stiff peak stage — when you lift the beater and the cream stands straight up forming a peak.  Keep in the refrigerator while completing the next step.
  3. In another bowl, combine the cream cheese and  powdered sugar.  Mix until smooth.  Fold this into the whipped cream  Cover and refrigerate.  If you are piping this frosting and it becomes too soft, just refrigerate the piping bag for a short while.
  4. A cake frosted with this must be refrigerated.  Before serving your cake, remove from the  refrigerator an hour or two before serving to warm up a bit.

Assembling the Key Lime Cake


Place the first cake layer (either room temperature or partially frozen) on the cake base or pedestal. Pipe a dam of whipped cream cheese frosting around the edge of the cake layer and spread the lime curd within it. You can pipe your dam using a disposable piping bag with the tip snipped away. If you want to skip the dam, just remember not to spread the curd all the way to the edge of the layer (to keep it all contained while stacking.

Spread the key lime curd layer with a layer of whipped cream cheese frosting. Repeat for the second layer and top with the third layer. Spread the top layer with key lime curd, and frost around the sides with whipped cream cheese frosting.

For a smoother finish, you can use a metal bench scraper (heated with water) to smooth around the sides of the cake. You can also freeze the cake for 15 minutes or so if you need to firm it up while applying the final coat of frosting.

I used a 2D piping tip to add borders, and sprinkled a little extra lime zest on top.

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28 Comments

  1. Do you know how adding a lime jello mix would help/hurt this recipe? I'm so used to a green color for key lime cake but I'm sure this is perfect. You haven't failed me yet lol Thank you!

    1. Hi Suzanne, we haven't tried it with a whole box but I'm sure it would be fine at least to add 2-3 tablespoons to give you a lime green color. Hope you enjoy it!

  2. If I don't use the lime curd in this recipe, will it still have enough key lime taste? I am just wanting to use frosting. Thanks.

    1. Hi Rachel, We think the lime curd filling adds additional flavor that is needed for the cake. There is lime juice in the cake but some of it bakes out and most of the lime flavor in the cake comes from the lime zest.

  3. Would this be too much batter for two 8-inch layers? I only have two pans, and I really don't want to spend all day baking. I suppose I could always just fill the two as full as I normally would for a 2-layer cake and toss the leftover batter? It looks so yummy, thank you! :)

    1. Hi Ann, there are so many different ways to doctor a cake mix, you'll find a lot of variation as you scroll from recipe to recipe. We hope that you enjoy it!