Lemon Sheet Cake

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Adapted from my beloved lemon layer cake recipe, this sheet cake version is just as soft and moist with the perfect zesty lemon flavor! It’s frosted with delicious lemon buttercream to make it extra bright and uses every part of the lemon for a fresh, natural lemon flavor in every bite. Baked in a 9×13 pan, it’s so fun (and easy!) to decorate and perfect for feeding a crowd of up to 30 people. It’s the ideal dessert for any Spring or Summer party! 

Why You’ll Love This Lemon Sheet Cake 

• Perfectly bright lemon flavor. The lemon flavor in this cake really shines! You’ll blend lemon zest into the sugar at the beginning of the recipe, add a little lemon extract to amplify it (optional, but amazing!), and use the juice of the lemon to make homemade buttermilk for adding at the end of the recipe. You’ll also use lemon juice in the frosting. Altogether, you’ll create a bright and zingy lemon flavor in every bite. 
• Super soft and moist. Between the cake flour, vegetable oil, and homemade buttermilk, this recipe yields a lemon cake that’s amazingly soft and moist (and stays that way for days)!
• Simple to make. This recipe uses simple ingredients and the instructions are super detailed to make it as easy as possible! Even if you’ve never made a cake from scratch before, I promise you can knock this one out of the park. 
• Easy and FUN to decorate. Contrary to a layer cake, sheet cakes are very straightforward when it comes to decorating. You can choose to frost and decorate the cake in the pan (like I did) or remove it from the pan and decorate it on a cake board. Either way, you won’t have to worry about filling and stacking cake layers or getting meticulous with the frosting.  
• Ideal for feeding a crowd. Not only is a sheet cake convenient to transport to an event, it’s easy to slice for serving a crowd. Depending on how you slice this cake, you’ll get between 24 and 30 slices. 

Lemon Sheet Cake Ingredients 

This recipe makes the softest lemon cake that is so moist and stays that way for days! Here are all the ingredients that make it special:

• Cake flour. To achieve the super soft texture, cake flour is a must. It produces a much fluffier cake than all-purpose (or plain) flour because of its lower protein content (the more protein in your flour the stiffer the dough and less ability to maintain moisture). You can find cake flour at most grocery stores, but if all you’ve got is all-purpose flour in your pantry, here are instructions for how to make your own cake flour. Keep in mind that if you do use the homemade version, the gram measurement will weigh more (331g instead of 265g) since all-purpose flour is heavier than cake flour.  
• Baking powder. Like many lemon cakes, this is the only leavening agent used. With the high acidity of the lemon in this cake, baking soda ends up producing too much carbon dioxide too quickly, which can cause the cake to sink. Baking powder doesn’t create that negative reaction with acidic ingredients, so it works double time in this recipe to make the perfect rise. 
• Granulated sugar. Not only does this sweeten the cake, it helps tenderize the crumb to create a super soft texture.
• Lemon zest + juice. In the beginning of the recipe, you’ll zest a lemon into the sugar and blend it all together to help the zest release all the natural oils. This creates an amazing lemon flavor from the beginning. We’ll add the lemon juice to the buttercream to take all the citrus flavor beyond!
• Lemon extract (optional). In addition to the zest in the cake, this is the best way to get a powerful lemon flavor. If you don’t have lemon extract, don’t worry! You can still make this cake without it and have an amazing lemon flavor – it will be a little more subtle in the cake, but once frosted with the lemon buttercream it’s absolutely delicious and totally lemony. 
• Unsalted butter + vegetable oil. Both butter and oil serve as the fats in this recipe. I like to use both because the butter adds rich flavor while the oil adds supreme moisture. I always use plain vegetable oil, but you can use any kind of neutral oil you’re used to baking with (canola, avocado, etc). 
• Egg whites. This cake uses all egg whites to keep it super light in color and texture. You can use fresh egg whites or ½ cup of carton egg whites. 
• Whole milk. I prefer whole milk in this recipe because it has a high amount of protein and fat, which yields a super rich texture and flavor. Like I previously mentioned, we’ll be adding lemon juice to the whole milk to create homemade buttermilk. The chemical reaction that happens between those two ingredients makes this cake extra moist. 

How to Get the Best Lemon Flavor

There’s a lot of lemon going on in this cake: lemon zest, lemon juice, and lemon extract. The recipe starts with zesting a lemon into the sugar and combining until the natural oils are released. The zest is much more powerful as a flavor additive than the lemon juice in a baked good – the juice tends to mostly evaporate in the baking process. Still, this recipe doesn’t waste the juice of that lemon you zested. Instead, we combine it with milk to make buttermilk for the end of the recipe, which will help make the cake supremely moist. 

The ingredient that lends the most powerful lemon flavor is lemon extract. Lemon extract is basically lemon zest that has been ultra-concentrated and therefore, takes the lemon flavor in the cake to the next level. I made this ingredient optional because even without the extract, this cake is still delicious and has a subtle lemon flavor that is amplified when frosted with the lemon buttercream. If you’re a diehard lemon fan, add the extract for the best lemon flavor! 

Bright & Tangy Lemon Buttercream 

The lemon buttercream used to frost and decorate this cake not only has amazing lemon flavor, it’s super easy to make! It’s a very straightforward American buttercream that has been altered to be slightly less sweet than the average. Lemon juice is added at the end of the recipe to create the bright, tangy lemon flavor. 

I did use a couple drops of yellow food coloring to create the sunny yellow color here. If you’d rather not use food coloring, the frosting will have more of a buttery yellow color naturally. Either way, it’s the perfect frosting for this soft and moist lemon sheet cake! 

How to Decorate a Lemon Sheet Cake

Once I made the lemon buttercream, I used it to frost a rustic finish on the lemon cake by simply swirling the frosting with an angled spatula. Once the surface of the cake was covered, I added the rest of the buttercream into a piping bag fitted with Wilton Tip 4B and piped a shell border around the edges of the cake before adding a few fresh lemon slices to a couple of the corners. 

I chose to decorate this sheet cake in the pan I baked it in for simplicity, but if you’d rather remove it from the pan for decorating, do it! The frosting recipe makes enough to frost the tops and sides of the cake and pipe that shell border in case that’s what you’d like to do. If you don’t plan on doing the shell border or any intricate piping, you can use the measurements shown in this lemon buttercream recipe to make less. 

Recipe FAQs

• Do I Sift the Flour Before or After Measuring? In this recipe, you’ll sift the flour before measuring. I recommend having a kitchen scale for the easiest workflow – you can place a bowl on the kitchen scale and sift the flour right into it, measuring exactly what you need without having to spoon and level the cake flour into cups.
• What if I Don’t Have Cake Flour? Cake flour makes this cake extra light and fluffy, so I do recommend making a trip to the grocery store for it. However, if you don’t have access to cake flour you can make your own homemade version using all-purpose flour (or plain flour) as a base. The instructions are in the notes section of the recipe card below.
• What if I Don’t Have Buttermilk? You can easily make a buttermilk substitute using whole milk + 1 tbsp of vinegar or lemon juice. Stir it together and let it sit for about 15 minutes before bringing it to room temperature if it’s not already. Don’t worry if the milk curdles, that’s actually a good thing here.
• Can I Use Carton Egg Whites Instead of Fresh? Yes. Substitute 1/2 Cup of pasteurized egg whites in place of the 4 large egg whites in the cake recipe. Just be sure to bring them to room temperature before adding them to the batter.
• How Tall is this Cake? The cake layer bakes up to about 1.5 inches (slightly shorter on the sides). The frosting and berries add another .5 inch or so, so altogether each slice ends up being about 2 inches tall. If you want a taller sheet cake with filling in between the layers, you can double the recipe. I’d recommend baking two separate cake layers vs. torting one taller cake layer.

More Sheet Cake Recipes You’ll Love

If you love making sheet cakes, here are some more recipes from my blog to add to your baking list: 

• Vanilla Sheet Cake
• Chocolate Sheet Cake
• Funfetti Sheet Cake 
• Strawberry Sheet Cake
• Red Velvet Sheet Cake

I hope you love this lemon sheet cake as much as I do! Let me know if you make it in the comments below and feel free to tag @sugarandsparrowco on Instagram to show me a photo. I love to see what you create!