Built on all the classic, favorite flavors of key lime pie, my key lime cake is fun, refreshing, and brilliantly flavored! It’s made with three moist, sweet vanilla cake layers, a tart key lime frosting, and (optional, but recommended) sky-high dollops of whipped cream. Recipe includes a how-to video tutorial!
Why You’ll Love This Key Lime Cake
- Cake layers: the cake layers are subtly infused with key lime flavor, but they still have a sweet vanilla cake taste, so the cake isn’t overpowered by tartness.
- Frosting: to achieve the most key lime flavor in the frosting, we’ll stir in a homemade lime curd. I first used this technique in my lemon frosting (this is a game changer for infusing flavor into frostings!).
- Decoration: a crown of stabilized whipped cream and miniskirt of graham cracker crumbs puts things over the top and gives everything an authentic key lime pie taste and feel.
- Technique: from the reverse creaming method used to make the tender cake layers to the curd-infused frosting, every bit of work you put into this cake will be well worth the reward.
A Few Things to Know
My current favorite cake, key lime cake isn’t just impressive to look at, it’s an absolute flavor masterpiece (if I do say so myself)! With subtly key lime flavored cake layers, a smooth and silky cream cheese key lime frosting, and generous dollops of whipped cream frosting (optional, but so recommended), it’s simultaneously decadent and totally refreshing for summer. A touch of graham cracker crumbs around the bottom adds a nice touch of sweetness and texture too!
The end result is the perfect balance of sweet and tart.
I went through many, many trials and variations developing this recipe and finally nailed the tender, soft, but slightly more dense crumb I was looking for in the cake layers. For the frosting, one that started with a cream cheese frosting base was the winner with my taste testers (and myself) every time.
Ingredients
Let’s chat about a few of the key ingredients in the cake itself, and then I’ll do the same for the frosting.
- Key lime juice. Key limes, let alone good, juicy ones, can be difficult to find depending on your location and time of year. You can substitute “regular” lime zest for the key lime zest, but for the juice I really recommend using a key lime juice. If you can’t find actual key limes, most stores carry the juice. Look for a brand called “Nellie & Joe’s Key West Lime Juice”, as that one works very well here (I have made the cake using this juice multiple times).
- All-purpose flour. I found that regular all-purpose flour (plain flour in the UK) worked best here (rather than cake flour).
- Butter & oil. Like so many of my cake recipes, I am using a combination of oil and butter to create a moist, flavorful crumb in this key lime cake. Oil is also especially helpful for preserving moisture in cakes that need refrigerated, like this one.
- Vanilla. Even though we are flavoring the cake with lime juice and zest, a touch of vanilla is still appropriate here. It is subtle, but softens the tartness of the limes a bit.
Frosting Ingredients
- Cream cheese. Just like when making key lime cheesecake, you must use full-fat, brick-style cream cheese for this key lime frosting. The spreadable kind sold in tubs (or the low-fat variety!) will be far too soft and you will have a runny frosting.
- Eggs. We’ll need just the yolks (so feel free to save the whites for coconut macaroons or meringues). This will form the base of our key lime curd, which we will beat into our frosting.
- Key Lime Juice. See my note above; I typically can’t find key limes when I want them, so I used bottled key lime juice (and while fresh will always be my preference, bottled works well here!).
- Graham cracker crumbs. These are optional, but for a key lime pie vibe, you can press some graham cracker crumbs up the sides after frosting. These add a nice texture too!
No vanilla here, as this would dampen the fresh lime flavor.
SAM’S TIP: Unlike many citrus fruits that reach their peak during the winter, limes are in season during the spring and summer months. So you might want to consider saving recipes like orange cookies and lemon cake for the winter, and make key lime cake when the weather is warm!
This is just an overview of the ingredients I used and why. For the full recipe please scroll down to the bottom of the post!
How to Make Key Lime Cake
Make the Cake Layers
- Whisk together the dry ingredients and sugar, then gradually stir in the butter one tablespoon at a time. Make sure you wait to add the next tablespoon of butter until the previous tablespoon is fully combined.
- Stir in the oil and lime zest until incorporated. You will be left with a sandy, crumbly mixture.
- Add your lime juice to a large glass measuring cup, then pour in milk until you reach a total of 1 ½ cups of liquid. This might seem like a strange measuring technique, but if you’ve ever made my buttermilk substitute, you’ll recognize it. By doing this, we are actually making a sort of buttermilk substitute. The scant cup of milk give us the proper amount of liquid and chemical reaction for the ultimate texture and flavor.
- Add the remaining wet ingredients to the milk mixture, then slowly pour it into your batter until combined. Scrape the sides and bottom of the bowl as needed and mix until you have a smooth, silky batter.
- Divide your batter between your cake pans and bake. I like to use the toothpick test to check for doneness; you want to see a few moist crumbs or a clean toothpick.
- Let the cakes cool for 10-15 minutes, then remove them from the pans and cool completely on a cooling rack.
Frosting
- Make the key lime curd, then pour it through a fine mesh strainer into a heatproof bowl. Let this cool completely before adding it to your frosting!
- Beat the butter and cream cheese until smooth, then gradually add 4 cups of the powdered sugar until incorporated.
- Gradually stir in the cooled key lime curd, working with one tablespoon at a time. Don’t do this too quickly or add too much, or you could break your frosting.
- Scrape the sides and bottom of the bowl, then taste test. Add the additional sugar if your frosting seems too soft, tart, or about to break.
Yes, making a homemade key lime curd is more time consuming than simply adding a splash of juice into the frosting, but it really nailed the flavor I was looking for, whereas just adding lime juice simply does not do the trick. I promise, the extra work is well worth it!
Assembly
- Level and frost your first cake layer, then repeat with the second layer. Add your final layer on top. If desired, do a crumb coat.
- Finish frosting your cake with an even layer around the outside.
- Press graham cracker crumbs up the sides of the cake, if desired.
- Pipe whipped cream swirls around the top of the cake and decorate as desired. I like to sprinkle lime zest and graham cracker crumbs on the tops of the swirls.
SAM’S TIP: Let the curd cool completely and add it gradually, or your frosting could break. This can be hard to fix (I talk a bit about this in my raspberry frosting post), so prevention is best.
Frequently Asked Questions
Regular lime zest will work fine for this key lime cake, but try your best to find key lime juice. I talk more about this in the recipe card below; I can usually find the juice in the fruit juice section of my grocery store.
Yes it does. The frosting and whipped cream won’t be stable at room temperature, so you need to store this cake in the fridge. Note that you should store this cake in an airtight container to prevent it from drying out in the fridge.
My key lime cake can also be made in a 9″ round pans, a 9×13″ pan, or as cupcakes. Just note that your bake time will be different for each, so keep an eye on your cakes as they bake.
This key lime cake is the perfect summer birthday cake! I can’t wait to hear how you like it.
Enjoy! And If you’re enjoying these fun and flavorful cakes, definitely check out my chocolate raspberry cake and new cannoli cake next!
Let’s bake together! Subscribe to my newsletter to be notified of all the newest recipes, and find my free recipe tutorials on YouTube 💜
Key Lime Cake
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Servings: 12 servings
Calories: 665kcal
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Instructions
Cake
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Preheat oven to 350F (175C) and thoroughly grease and flour the sides of three 8” cake pans, tapping out any excess flour, and line the bottoms with parchment paper.
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In a large bowl (or the bowl of your stand mixer fitted with the paddle attachment), combine flour, sugar, baking powder, baking soda, and salt.
2 ⅔ cups (333 g) all-purpose flour, 2 cups (400 g) granulated sugar, 1 teaspoon baking powder, ½ teaspoon baking soda, 1 teaspoon table salt
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With mixer on low speed, add softened butter one Tablespoon at a time, allowing each Tablespoon to be fully incorporated into the dry ingredients before adding the next. Once all butter is added, the mixture will have a sandy, crumbly texture.
½ cup (113 g) unsalted butter
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Add oil and lime zest and stir until well combined. Set aside.
¼ cup (60 ml) avocado, 1 Tablespoon lime or key lime zest
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Add the key lime juice to a large measuring cup (at least 2-cup), then add the milk until it reaches the 1 ½ cup line and whisk to combine.
1 ½ Tablespoons key lime juice, 1 ½ (333 ml) scant cups whole milk
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Add eggs and vanilla to the milk mixture and whisk to combine.
2 large eggs, 1 teaspoon vanilla extract
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Turn mixer to low speed and slowly add the milk mixture into batter until fully combined, pausing to scrape the sides and bottom of the bowl as needed. Batter should be uniform, silky and smooth.
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Evenly divide batter into prepared pans (if weighing batter, each pan should have approximately 460 grams of batter) and bake in the center rack of preheated 350F (175C) oven for 26-28 minutes, or until a toothpick inserted in the center of each cake comes out clean or with a few moist crumbs.
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Allow cakes to cool in their pans for 10-15 minutes, then run a knife along the edge of the pan to loosen from the edges and carefully invert onto a cooling rack to cool completely. While cakes are cooling, prepare your frosting.
Curd
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In a small, non-reactive saucepan (see note) whisk together egg yolks, key lime juice, sugar, and salt.
2 large egg yolks, ⅓ cup (80 ml) key lime juice, 2 Tablespoons granulated sugar, ¼ teaspoon table salt
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Add butter and cook over medium/low heat, whisking constantly until mixture is thickened. This will take several minutes; once it is thickened the whisk should start to leave trails through the curd, and it should coat the back of a spoon.
2 Tablespoons (28 g) unsalted butter
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Pour curd through a fine mesh strainer into a heatproof bowl. Allow to cool completely before proceeding (this may be placed in the refrigerator to cool faster).
Frosting
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In a large mixing bowl, use an electric mixer to beat softened butter and cream cheese until smooth and creamy.
¾ cup (170 g) unsalted butter, 6 oz (170 g) cream cheese
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Gradually add 4 cups (500g) of powdered sugar until completely incorporated.
4-5 cups (500-625 g) powdered sugar
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Add the cooled curd, one Tablespoon at a time, until you’ve added 5-6 Tablespoons. Be sure to scrape the sides and bottom of the bowl to be sure all ingredients are thoroughly combined. If the frosting seems too soft, too tart, or on the verge of breaking add the remaining sugar as needed.
Assembly
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Once cakes are cooled, level the tops if necessary.
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Frost each layer evenly with the prepared frosting. Evenly frost the outside of the cake with the remaining frosting.
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Gently press graham cracker crumbs around the bottom of cake, about a quarter of the way up.
¼ cup (28 g) graham cracker crumbs
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Pipe, swirl, or dollop stabilized whipped cream frosting over the top of the cake, if using. Decorate with additional graham cracker crumbs or lime zest, if desired.
½ batch Stabilized whipped cream frosting
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Allow to chill in the refrigerator for at least 30 minutes before cutting and serving. Enjoy!
Notes
Key limes
Key limes can be difficult to find across the US depending on location and time of year. You can substitute “regular” lime zest for the key lime zest, but for the juice I really recommend using a key lime juice. If you can’t find actual key limes, most stores carry the juice. Look for a brand called “Nellie & Joe’s Key West Lime Juice”, that one works very well here (I have made the cake using this juice myself multiple times).
Saucepan for curd
Choose a small one made of a non-reactive metal like stainless steel or an enameled ceramic pot. Avoid reactive metals (like cast iron or aluminum) that could react with the acidity of the lime juice and make your frosting taste metallic.
Lime Curd
Curd may be prepared up to 3 days in advance of making the frosting. This recipe should yield approximately 6 Tablespoons of a very tart key lime curd. While you can substitute an equal amount of store-bought curd, it may alter the desired taste a bit and homemade/as-written is best.
Decorating: Whipped Cream Topping
To give this cake a real key lime pie feel, a whipped cream topping really adds a nice but optional touch. You can skip this entirely or if you prefer, but I recommend making a half-batch of my stabilized whipped cream frosting and piping this over the top of the cake (this can be done in advance and will hold its shape for days, unlike classic homemade whipped cream). I used my Ateco 848 piping tip to decorate the cake as seen in pictures and the video.
Storing
Store in airtight container in the refrigerator for up to 4 days. Cake may also be tightly wrapped and frozen for up to 3 months. I recommend thawing overnight in the refrigerator before serving.
Nutrition
Serving: 1serving | Calories: 665kcal | Carbohydrates: 100g | Protein: 6g | Fat: 28g | Saturated Fat: 17g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 8g | Trans Fat: 1g | Cholesterol: 130mg | Sodium: 387mg | Potassium: 99mg | Fiber: 1g | Sugar: 76g | Vitamin A: 932IU | Vitamin C: 3mg | Calcium: 61mg | Iron: 2mg
Nutritional information is based on third-party calculations and should be considered an estimate only. Actual nutritional content will vary based upon brands used, measuring methods, cooking method, portion sizes, and more.
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