Key Lime Sheet Cake is the perfect balance of sweet and tart, packed with citrusy goodness in every bite. If you’re craving a little sunshine in dessert form, this is the cake for you!
Recently I found an amazing deal on a big bag of limes at the grocery store. At first, I put them to good use in my favorite savory dishes. Zesty pico de gallo, Brazilian moqueca, and fresh guacamole. But even after all that, I still had so many left over! What to do? I usually consider lime desserts a summertime thing. But I’ve decided that they’re just as refreshing off-season. Plus, there’s something about making a bright, citrusy cake that feels like manifesting warm weather. I know that’s something we’re all craving right now!
Among my long list of bookmarked recipes, I found the perfect citrusy inspiration – Toomer’s Lemonade Sheet Cake, featured in Southern Living magazine. It’s a recipe that hails from Toomer’s Drugs in Alabama. The drugstore, which dates back to the 1890s, later became a souvenir and ice cream shop on the Auburn campus and still sells the famous sheet cake. With my bounty of limes, I decided to turn it into a Key Lime Sheet Cake. I’m sure the lemonade version is wonderful. But let me tell you, everyone who tastes this lime version loves it. I’m not sure it’s better than the original, but it has to be equally as tasty!
Dry Ingredients and Wet Ingredients
Start by whisking together flour, baking soda, and salt in a large mixing bowl. Easy peasy. Set the dry mixture aside while you prepare the wet ingredients.
The wet ingredients are just two: buttermilk and fresh lime juice. If you have bottled key lime juice, then that will work, too. In a large measuring cup with a spout, combine the buttermilk and lime juice. Stir the mixture well and set it aside. The acidity in the buttermilk and lime juice will help create a tender crumb in the cake.
Creamed Ingredients
In the bowl of an electric mixer, beat the butter and granulated sugar together until the mixture is light and fluffy, about three minutes. Add 3 tablespoons of lime zest (If you need a good zester, I like this one!) and vanilla extract, mixing until well incorporated. Add the eggs in one at a time, beating thoroughly after each addition. This step ensures a smooth, even texture in the batter.
With the mixer on low speed, alternate adding the dry ingredients and the buttermilk mixture to the creamed butter mixture, starting and ending with the dry ingredients. Mix until just combined, being careful not to overmix.
Bake in a 13×18-inch Pan
Let’s talk about the pan for a sec – it’s a big one! I used this KitchenAid 13x18x1-inch pan, and it perfectly held all the batter and baked evenly. However, if you don’t have that exact size, then similar sized pans will work. If you’re an avid cake baker, you may already have Wilton’s 12x18x2-inch large sheet cake pan, which has deeper edges, and will also work. I haven’t tested it myself, but in theory, you could halve this recipe and bake it in a 13x9x1-inch pan. Since the batter will be about the same thickness, the baking time should be similar, but I’d start checking for doneness a little earlier, around the 18-minute mark.
Preheat your oven to 350°F and grease and flour the sheet pan. Spread the batter evenly into the prepared pan, smoothing the top with a spatula. Bake for 18-24 minutes, or until a toothpick inserted in the center comes out clean. While the cake bakes, prepare the lime syrup.
Poke Holes and Drench with Lime Syrup
Prepare the lime syrup by combining granulated sugar and fresh lime juice in a microwave-safe bowl. Microwave for about a minute, stirring until the sugar dissolves completely. Using a fork, poke holes all over the surface of the cake, then brush the syrup evenly across the top. This step infuses every bite with bright lime flavor and keeps the cake moist. Allow the cake to cool completely before frosting.
Frost and Decorate
For the cream cheese frosting, beat the cream cheese and butter together in an electric mixer until smooth and fluffy. Add the lime zest and a little sea salt, mixing to combine. Gradually add the powdered sugar, a little at a time, beating well after each addition. Continue to beat until the frosting is light and creamy.
Spread the frosting evenly over the cooled cake, using an offset spatula to create swirls. Finish with a sprinkle of lime zest and garnish with thin lime wheels. The sliced strawberries are optional, but so nice for a beautiful, fresh presentation.
This Key Lime Sheet Cake bakes up thin and even in a shallow pan, but don’t let its modest height fool you – it’s incredibly moist. Thanks to the lime syrup, which soaks into every bite, the cake stays soft, tender, and full of zesty flavor without feeling heavy. And then there’s the cream cheese frosting with just the right amount of creaminess to complement the tartness of the cake.
This recipe feeds a crowd of people – so consider making it for your next picnic, potluck or family gathering. Personally, I’m eyeing it for this year’s Easter dessert.
Related recipe: Mojito Cupcakes
Key Lime Sheet Cake
Cake
- 3 cups all-purpose flour
- 1 teaspoon baking soda
- 3/4 teaspoon fine grain sea salt or kosher salt
- 1 cup buttermilk at room temperature
- 1/2 cup fresh lime juice from 3 large limes
- 1 cup unsalted butter at room temperature
- 1 3/4 cups granulated sugar
- 3 tablespoons lime zest from 3 large limes
- 1 teaspoon vanilla extract
- 4 large eggs at room temperature
Lime syrup
- 1/2 cup granulated sugar
- 1/4 cup fresh lime juice from 2 large limes
Cream cheese frosting:
- 8 oz. cream cheese at room temperature
- 1/2 cup unsalted butter at room temperature
- 3 tablespoons fresh lime zest from 3 large limes
- 1/4 teaspoon fine grain sea salt or other fine grain salt
- 4 cups powdered sugar
Toppings
- 1 teaspoon lime zest
- 1 lime cut into thin wheels
- 4 large fresh strawberries optional
Cake
-
Preheat the oven to 350°F. Coat a 13×18-inch sheet pan with flour based baking spray, or grease and flour the pan.
-
In a large mixing bowl, whisk together the flour, baking soda, and salt. In a large glass measuring cup with a pour spout, mix together the buttermilk and lime juice. Set aside.
-
In the bowl of an electric mixer fitted with the paddle attachment, beat together the butter and granulated sugar until light and fluffy, about 3 minutes. Add the lime zest and vanilla extract. Beat again to combine. Add eggs one at a time, beating well after each addition. Scrape down the bowl occasionally to ensure even mixing.
-
With the mixer on low speed, add the flour mixture and the buttermilk mixture alternately to the creamed butter mixture; begin and end with flour. Scrape down the bowl and beat again briefly.
-
Spread the batter evenly into the prepared pan. Bake for 18-24 minutes or until a toothpick tester inserted near the center comes out clean.
Lime syrup
-
Combine the sugar and lime juice in a microwaveable bowl. Microwave on 100% power for 1 minute; stir well until the sugar dissolves. If sugar granules are still present, microwave an additional 30 seconds and stir again.
-
When the cake is done, use a fork to poke holes all over the cake. Using a pastry brush, cover the entire cake evenly with the lime syrup. Allow the cake to cool in the pan completely on a wire rack, about 1 hour.
Cream cheese frosting
-
In the bowl of an electric mixer fitted with the whip attachment, beat the cream cheese and butter until fluffy, about 3 minutes. Add the lime zest and salt, and then mix again. Add the powdered sugar one cup at a time, beating well after each addition. Beat on high speed until the mixture is light and fluffy.
-
Cover the entire cake with the cream cheese frosting.
Toppings
-
Sprinkle lime zest over the frosting (or grate the zest of a lime directly onto the frosting as in the video).
-
Arrange lime wheels in the corners and in the center of the cake. Slice the strawberries within 1/4 inch of the green tops; fan them slightly and arrange on top of the cake, if using.
- Limes: You don’t need to use key limes for this Key Lime Sheet Cake—regular (Persian) limes work just fine! While key limes have a more intense, slightly floral tartness, they can be harder to find and require juicing a lot more of them to get the same amount of juice. Regular limes provide plenty of bright, citrusy flavor. If you want to get closer to the key lime flavor, you can use bottled key lime juice, but fresh lime juice (of any variety) will still make a delicious cake!
- Perfect Lime Slices: For ultra-thin, even lime slices to use as a garnish, a mandoline slicer is your best friend! But be careful, those things are sharp! Set it to a thin setting and carefully slice the lime for beautiful, delicate rounds. If using a knife, make sure it’s very sharp to avoid crushing the lime.
- Even Better the Next Day: This cake tastes even more incredible the next day! As it sits, the oils from the lime zest infuse into the cake and frosting, deepening the citrus flavor and making every bite even more vibrant and delicious. If you have time, make it a day ahead for the best results.
- Storage: Store the cake covered in the refrigerator for up to 5 days. Let it sit at room temperature for about 30 minutes before serving for the best flavor and texture.