How to make sheet cake from a layer cake recipe

At King Arthur Flour, we believe that one of the best parts of baking is sharing with others. Whether you try a new recipe with a friend or you bring a neighbor a homemade treat, baking is most rewarding when shared. But with so many suitable recipes to choose from, how do you pick what to make?

We've got you covered — bake cake, of course! You’re guaranteed to make someone’s day if you bake them cake. And don't bake just any cake. Bake a sheet cake. 

Sheet cake: it's quick to frost, easy to decorate, travels well, and can feed a crowd. 

There are a number of single-layer cake recipes on our website (54 to be exact), but don't confine yourself to these recipes. We'll show you how to bake a layer cake recipe in a 9" x 13" pan so you're always ready to bake and share sheet cake. 

If you want to convert a cake recipe but don't have a 9" x 13" pan, check out our blog, The essential alternative baking pan sizes, for more options.

Which recipes can be turned into a sheet cake?

When choosing a recipe to convert to a 9" x 13" sheet cake, there are a few things to keep in mind. For best results, choose a cake recipe that calls for baking the batter in two or three 8” round pans, or two 9” round pans.

You're looking for recipes that make about 6 cups of batter — this amount fits perfectly into a 9” x 13” pan.

Keep in mind, not all cake recipes can be seamlessly converted to a sheet cake. Skip recipes that don’t use a mixing method of creaming, blending, or the paste method. Anything that's not a standard cake tends to misbehave in a sheet pan. For example, sponge cakes (like Angel Food Cake) or cakes with a meringue layer are best left in the original format the recipe calls for.

What better recipe to show you how to make sheet cake than our 2019 Recipe of the Year, Classic Birthday Cake? It's a showstopping centerpiece for special celebrations in its original layer cake form, but it works beautifully as a sheet cake, too.

Whether you have your own favorite layer cake recipe or you’re ready to use our Classic Birthday Cake, we’ll teach you everything you need to know to transform a layer cake into a sheet cake, a format that’s ideal for sharing.

Prepare your pan

Once you've chosen your recipe, it's time to start baking.

First step: make sure your pan is ready for the batter. Lightly grease a 9” x 13” pan with non-stick spray. You might also consider using a parchment paper sling to line your pan if you’d like to easily remove the cake before serving.

After you've prepared the pan, preheat the oven to 325°F (or the temperature called for in your recipe), and gather your ingredients.

Mix up the batter

Prepare the batter as described in your recipe. You don’t need to make any changes, even though you're converting the recipe from a layer cake to a sheet cake.

Once the batter is smooth and ready to be baked, pour it into the prepared cake pan.

How long do you bake a sheet cake?

Here are some guidelines for how long to bake your sheet cake when starting with a layer cake recipe:

• Two 8” rounds to a 9” x 13” pan: Increase the bake time by 20% to 25%
• Three 8” rounds to a 9” x 13” pan: Increase the bake time by 25% to 30%
• Two 9” rounds to a 9” x 13” pan: Increase the bake time by 30% to 40%

This will give you an idea of when you should start checking your cake for doneness. For example, if your recipe calls for baking in two 8" rounds for 38 to 42 minutes, multiply the low end of the range by 1.2 and the high end of the range by 1.25. This means the sheet cake version should take about 45 to 52 minutes to bake. 

Remember to check your cake early and often, as these general rules simply help estimate the bake time. Some cakes might need more or less time to bake as a sheet cake, depending on the recipe.

The key to making sure your cake is perfectly baked is to use your senses. The center of the cake should feel springy to the touch. A paring knife or toothpick inserted into the center of the cake should come out mostly clean. Best of all, your kitchen should smell heavenly when the cake is done baking.

For the Classic Birthday Cake made in a 9” x 13” pan, bake it for 45 to 48 minutes at 325°F until it tests done.

How much filling and frosting do I use?

If your recipe calls for filling (rather than frosting) between the top and bottom layers, you’ll probably want to skip it. Sheet cakes aren’t easy to split and fill. You’re welcome to try if you’re feeling adventurous, though; if the original recipe calls for a single layer of filling, you’ll want to make a double batch for your sheet cake in order to ensure there’s enough to cover the entire surface.

As far as frosting goes, we find 3 cups is about right to frost a 9" x 13" cake, plus some extra for piping and decorating. 2 cups will suffice if you’re OK with a thin layer of frosting; 4 cups will give you some excess.

In general, frosting recipes formulated for 8” or 9” layer cakes will make more than the necessary 3 cups of frosting.  You’re welcome to make a full batch and simply freeze any extra; most frostings freeze quite well.

Alternately, you can downsize the frosting recipe. Try scaling down the frosting to 3/4 of a batch for your 9” x 13” sheet cake. For you lovers of American-style buttercream, start with about 12 tablespoons of butter (or shortening) to end up with the right amount of frosting.

Assemble your sheet cake

Once the cake is fully cooled, apply the frosting using the tool of your choice. (I can’t imagine using anything but a small offset spatula for this task.)

If you’re looking for decorating inspiration, check out our cake styling guide. The cakes shown are all layer cakes, but many of the techniques — swoops, waves, scallops, and sprinkles — can add personality to sheet cakes too.

My go-to decoration includes edible flowers, berries, and natural sprinkles. Let your imagination be your guide.

Bake and share

Now that you know how to bake a perfect sheet cake, you can bake and share with someone in your life. We’re excited to let you know who we have been baking for recently.

We’ve partnered with the Upper Valley Haven in White River Junction, Vermont, a non-profit organization that serves people struggling with poverty. The Haven provides food, shelter, education, and other support to those in need in our community.

As bakers, we want to share the joy that comes from having something sweet to celebrate a special day. What day is more special in the life of a child than a birthday?!

We thought we'd put our Classic Birthday Cake recipe to good use and bake birthday cakes for children at the Haven as a fun way to spread happiness.

Birthday cakes for the Haven

As employee-owners, we’re each allotted 40 hours of paid volunteer time per year, with 10 of those hours dedicated to volunteering for organizations focused on hunger relief. By baking for the Haven, we can use our volunteer time to bring some happiness to children in our community.

The sheet cake version of our Classic Birthday Cake is the perfect canvas to decorate in celebration of birthdays at the Haven. Here are some snapshots of the birthday cake baking we've done throughout the year:

Bakers who wanted to avoid using a piping bag but still add writing to the cakes came up with some outstanding solutions.

Occasionally, there aren't any children with birthdays during a certain month. In these cases, our bakers make a seasonally-themed cake and everyone enjoys a special treat just because they can!

Whatever the format — sheet cake, cupcakes, or layer cake — the treats are certainly appreciated by all at the Haven. For some of the children, it's the first time they've ever had a birthday cake made for them. We're truly honored to provide the children with something that makes them feel celebrated.

We encourage you to bake and share with someone in your community, so you too can experience the rewarding feeling that comes from baking for others. It's sweeter than chocolate-frosted birthday cake. 

If you'd like some inspiration, be sure to check out all of the layer cake recipes we have on our recipe site. Happy baking! 

Thanks to Jenn Bakos for taking most of these photos, to the King Arthur Flour employee-owners who submitted photos of cake baking, and to the Haven for sharing photos of the children enjoying birthday cake!