Best Key Lime Cake
For those who crave a burst of citrus with every bite, key lime cake is a dream come true. This cake strikes the perfect balance between sweetness and tartness, delivering a taste that’s both invigorating and indulgent. With every mouthful, you’ll enjoy the delicate blend of fresh key lime zest, fluffy cake layers, and creamy, buttery frosting. Ideal for summer gatherings, birthdays, or any celebration that calls for a light yet flavorful dessert, this key lime cake is sure to leave a lasting impression.
Ingredients Breakdown: Essential Elements for Success
This cake’s success depends on using fresh, high-quality ingredients to create a flavor that’s as vibrant as it is delicious.
For the Cake Layers: The base of the cake is a combination of cake flour, granulated sugar, butter, and neutral oil, ensuring each bite is soft yet moist. The real magic comes from the key lime zest, which infuses the cake with a distinctive tangy aroma. The whole milk and vanilla extract add richness and depth, complementing the zest’s sharpness, while whipped egg whites are gently folded in to create a light, airy texture.
For the Key Lime Curd: The key lime cake curd is a tart, citrusy filling that elevates this cake to a new level. Made with fresh key lime juice, egg yolks, and granulated sugar, the curd is thickened with a touch of cornstarch and enriched with butter. This concentrated lime filling pairs beautifully with the soft cake layers, delivering a tangy pop in every bite.
For the Swiss Meringue Buttercream: This luxurious frosting is smooth, silky, and just slightly sweet, providing a gentle contrast to the tangy curd. Made from egg whites, sugar, and butter, the buttercream’s creamy texture holds its shape perfectly, making it an ideal choice for decorating. The touch of vanilla rounds out the flavor, ensuring a harmonious balance between the sweet and citrusy elements of the cake.
Step-By-Step Instructions for Perfect Layers
Preparing the Cake Layers: Begin by preheating the oven and prepping three 6-inch cake pans with parchment paper. Rubbing the lime zest into the sugar releases essential oils, creating a fragrant sugar base that permeates the cake. Once the dry ingredients are mixed, small cubes of butter are incorporated until the texture resembles wet sand. After adding oil, milk, and vanilla, whipped egg whites are folded in for an airy, light batter. Dividing the batter evenly ensures each layer bakes uniformly, yielding cakes that pull away from the pan edges when ready. Freezing the cooled layers makes frosting a breeze, helping each layer maintain its shape.
Making the Key Lime Curd: To prepare the curd, whisk the egg yolks, sugar, cornstarch, and salt until smooth. Key lime juice is added, and the mixture is gently cooked over medium heat, stirred constantly for a thick, silky curd. Once the curd reaches the desired consistency, it’s strained to remove any solids and mixed with zest, enhancing the bright lime flavor. Chilling the curd ensures a firm consistency, ideal for spreading between the cake layers.
Crafting the Swiss Meringue Buttercream: Begin by cleaning the mixer bowl and whisk with vinegar to ensure no grease interferes with the meringue. The egg whites, sugar, and salt are warmed over simmering water, then whisked until medium peaks form. Once the mixture reaches 160°F and the sugar dissolves, beat on high to achieve stiff peaks, then cool the meringue to 85°F before gradually incorporating butter. The buttercream may appear curdled initially but will smooth out with persistent mixing, resulting in a creamy, spreadable frosting.
Assembly: Building and Decorating Your Key Lime Cake
Layering and Filling: Place the first cake layer on a cake stand or plate. Pipe a ring of buttercream around the edge, creating a barrier to hold the key lime curd within the layer. Spread an even layer of curd in the center, repeating with the next layer to build the cake. This layering of curd and buttercream adds texture and tangy flavor to each bite.
Frosting and Final Touches: After adding the final cake layer, spread a generous amount of buttercream on top, using an offset spatula to smooth it out and cover the sides. This initial coating seals in crumbs, creating a neat foundation for the final frosting layer. Garnish with fresh key lime zest, edible flowers, or even thin lime slices for a striking presentation.
Recipe Tips & Frequently Asked Questions
- How to Zest and Juice Key Limes Efficiently: Use a microplane for fine zest, avoiding the bitter white pith. Roll limes under your palm to release more juice.
- Perfecting the Swiss Meringue Buttercream: Maintain the right temperature and beat the mixture patiently if it appears curdled.
- Making Ahead: Prepare cake layers, curd, and buttercream in advance, storing each separately and assembling when ready.
- Can I Use Regular Limes Instead of Key Limes? Substitute with standard limes if necessary, but reduce zest quantity slightly, as regular limes are more potent.
- How Do I Store This Cake? Store the assembled cake in the refrigerator for up to three days or freeze layers and buttercream separately for longer storage.
- Can I Make This Cake Gluten-Free? Replace cake flour with a gluten-free baking blend, adjusting liquids if needed for consistency.
What to Serve with This Key Lime Cake
Refreshing Beverages: Pair this key lime cake with a chilled glass of iced tea, limeade, or a crisp, dry white wine to complement the citrus notes. A mojito or sparkling water infused with lime also makes a lovely addition to the table.
Complementary Desserts: Small tropical-inspired desserts, like coconut macaroons or pineapple sorbet, beautifully accompany the cake. These treats enhance the overall tropical theme and offer delightful contrast in flavor and texture, rounding out a vibrant dessert spread.
Wrapping Up: Enjoying Your Key Lime Cake
This key lime cake is a celebration of citrus, bringing zest, sweetness, and an undeniable freshness to the table. It’s the ideal treat for any special occasion, but it’s also a great choice for those days when you simply crave something a little more indulgent. Once assembled, this key lime cake is a showstopper, both in taste and presentation. Customize with garnishes, from candied lime slices to delicate edible flowers, to make it your own.
Key Lime Cake
Ingredients
For the cake layers:
- 210 g 1 ¾ cups cake flour
- 76 g 5 ½ tbsp unsalted butter, room temperature
- 50 g ¼ cup neutral oil
- 2 teaspoons baking powder
- 162 g ¾ cup + 1 tbsp granulated sugar
- Zest of 5 key limes
- 227 g 1 cup whole milk, at room temperature
- ½ teaspoon salt
- 2 teaspoons vanilla extract
- 2 egg whites
For the key lime curd:
- 3 egg yolks
- 100 g ½ cup fresh key lime juice
- 35 g 2 ½ tbsp unsalted butter
- 100 g ½ cup granulated sugar
- 10 g 1 tbsp cornstarch
- ½ teaspoon kosher salt
- Zest of 5 key limes
For the swiss meringue buttercream:
- 145 g about 4 egg whites
- 340 g 1 ½ cups unsalted butter, at room temperature
- 300 g 1 ½ cups granulated sugar
- 2 teaspoons vanilla extract
- ½ teaspoon salt
Instructions
For the cake layers:
- Preheat your oven to 350°F (175°C). Prepare three 6-inch cake pans by greasing them lightly and lining each with parchment paper.
- In the bowl of a stand mixer, combine the granulated sugar and lime zest. Rub together with your fingertips until the sugar becomes fragrant and resembles damp sand.
- Add the cake flour, baking powder, and salt into the sugar mixture, blending on low speed.
- Cut the butter into cubes and add it gradually to the dry ingredients, mixing until the texture is like fine sand.
- Pour in the oil, milk, and vanilla extract, and mix just until everything is combined.
- In a separate bowl, use a hand mixer to whip the egg whites until they reach medium peaks.
- Gently fold the whipped egg whites into the batter using a rubber spatula, mixing carefully until just incorporated.
- Evenly distribute the batter among the prepared cake pans.
- Bake for approximately 22-25 minutes, or until the edges of the cakes pull slightly away from the pans. Transfer the cakes to a wire rack to cool completely.
- Once cool, wrap each layer in plastic wrap and freeze until you’re ready to frost and decorate. (Frozen cake layers make for easier frosting.)
For the key lime curd:
- In a medium bowl, whisk together the egg yolks, sugar, cornstarch, and salt until the mixture is smooth and slightly lightened in color. Stir in the key lime juice until thoroughly blended.
- In a medium saucepan over low-medium heat, melt the butter.
- Add the egg yolk and lime juice mixture to the melted butter. Raise the heat to medium, stirring constantly with a rubber spatula for 3-4 minutes, until the curd thickens and bubbles form at the center.
- Remove from heat immediately, pouring the curd through a fine-mesh sieve into a clean bowl. Stir in the key lime zest, transfer the curd to a jar, and chill for at least 1 hour or preferably overnight.
For the swiss meringue buttercream:
- Begin by wiping down the bowl of a stand mixer and the whisk attachment with a bit of white vinegar to remove any grease.
- Place the egg whites, sugar, and salt in the bowl. Whisk together until well combined.
- Set the bowl over a saucepan of simmering water, stirring frequently until the mixture reaches 160°F (71°C) or until the sugar has dissolved and the mixture is no longer grainy to the touch.
- Transfer the bowl to the stand mixer with the whisk attachment, beating on medium-high until the meringue holds medium peaks.
- Add the vanilla extract, then continue beating until stiff peaks form.
- Lower the mixer speed and wait until the meringue cools to around 85°F (29°C).
- Gradually add the butter, a few cubes at a time, ensuring each piece is fully incorporated before adding more. The buttercream may look curdled at first, but continue beating, and it will smooth out.
- Once the buttercream comes together, switch to the paddle attachment and mix on low speed until it becomes smooth and creamy.
For assembly:
- Place the first cake layer on your cake stand. Pipe a rim of buttercream around the edge, creating a barrier. Fill the center with a layer of key lime curd.
- Add the second layer of cake and repeat with the buttercream dam and curd filling.
- Place the final cake layer on top and add a few scoops of buttercream. Smooth the top with an offset spatula, spreading the excess buttercream around the sides.
- Decorate as desired, finishing with a sprinkle of key lime zest on top. Enjoy!