Chocolate sheet cake is a moist and tender homemade cake with rich chocolate flavor. The velvety whipped chocolate buttercream frosting makes it perfect for chocolate lovers! This recipe can be made in three different pan sizes - 9x13, 13x18, or as a round layer cake.
After many reader requests, I've made sheet cake recipes out of my much-loved cupcake recipes, like vanilla sheet cake and lemon sheet cake. Today it's chocolate's turn - we're turning my chocolate cupcakes recipe into a cake!
This cake is made with simple baking ingredients and can be prepared in three different pan sizes. Make this cake in a 9x13 sheet pan, 13x18 sheet pan, or as a 9-inch two layer cake. Instructions for each are included in the recipe card.
Serve chocolate sheet cake at your next picnic, celebration, or birthday party. It's perfect any time of year!
What size pan to use
This recipe works in three different sizes:
- 9x13 baking pan (with 2 inch sides)
- Two 9-inch round cake pans
- 13x18 half sheet pan (with 1 inch sides)
So, what size do you choose? This is totally up to personal preference. I have tested this recipe in all three sizes (as shown above) and they all turn out tender, moist, and delicious.
Both the 9x13 and 13x18 sheet cakes remain in the pan after baking. Simply frost, slice, and serve! Round cakes need to be removed from their pans, trimmed, assembled, and frosted. This takes extra skill, patience, and (potentially) extra frosting.
Suggested baking pans:
- Nordic Ware Classic Metal 9x13 Covered Cake Pan
- Natural Aluminum Nordic Ware Commercial Baker's Half Sheet (2 Pack)
- Nordic Ware 9" Round Natural Aluminum Cake Pans (2 Pack)
Ingredients and substitutions
Since baking is an exact science, I do not recommend substituting any ingredients in this recipe. If you do not have the listed ingredients on hand, I recommend searching for a recipe that includes the ingredients available to you.
- All-purpose flour - I use all-purpose flour in my chocolate cakes because the wet ingredients are heavier and thicker (specifically the oil and buttermilk), so the batter benefits from the added structure of AP flour.
- Cocoa powder - You'll want to use natural cocoa powder for this recipe, not Dutch-processed cocoa powder. Natural cocoa powder is more acidic than Dutch cocoa powder. When paired with the leavening agents in this recipe it gives your cake the proper rise. What happens if you use Dutch cocoa anyway? Your cake will rise less in the oven and have a darker color.
- Leavening - You'll need a combination of both baking soda and baking powder to get the proper lift.
- Salt - Enhances the flavor of your cake without making it "salty".
- Granulated sugar - Sugar adds sweetness, moisture, and acts as a preservative in your cake. I have not tested this recipe with sugar substitutes. If you don't want to use granulated sugar in your cake, I highly recommend searching for a chocolate cake recipe made with the sugar substitute you'd like to use.
- Eggs - Eggs add structure and moisture to your cake. Room temperature eggs are best for baking because they blend seamlessly into the batter without lumps or streaks.
- Buttermilk - Adds moisture, a hint of tang, and the proper acidity to your cake batter. If you don't have buttermilk on hand, a buttermilk substitute can be made. In a liquid measuring cup, add 1 tablespoon of white vinegar. Fill to the 1-cup line with whole milk and allow to set for 5 minutes. This makes a proper buttermilk substitute with the right amount of acidity for the recipe.
- Warm water - Added to the batter to thin it slightly so your cake rises properly. Without water, the batter is too dense and heavy, making it likely to sink in the center.
- Vegetable oil - Adds moisture to your cake. I prefer to use oil in chocolate cake for a few reasons. Oil gives cake a velvety, extra-moist texture that can't compare to cakes made with butter. While butter adds a better overall flavor to recipes like vanilla cake, it can't compete with the strong flavor of cocoa powder, making it an unnecessary addition.
- Vanilla extract - Enhances the flavor of your cake.
Cake batter tips and tricks
- Preheat your oven before beginning. For best results, your cake should go in the oven as soon as the batter is poured into the pan.
- Eggs should be room temperature before beginning. Room temperature eggs blend seamlessly into the batter without leaving and streaks or lumps. To bring eggs to room temperature, place on the countertop 30 minutes before beginning. You can also place whole eggs into a bowl and cover with warm tap water. Using this method, your eggs will come to room temperature in about ten minutes.
- Sift or whisk your dry ingredients together. This removes clumps and helps make a smooth, even batter.
- There's no need to use a hand mixer or stand mixer for the cake batter (but you will want one for the included frosting recipe). Use a spoon or a whisk to mix your wet ingredients together, then use a spoon to add the dry ingredients.
- Whisk your wet ingredients together just enough to incorporate them. Over-whisking can add unstable air to the batter, causing your cake to rise up and then fall while baking in the oven.
- Mix your dry ingredients just enough to incorporate them into the batter. Overmixing can overwork the gluten, causing your cake to turn out tough.
- Once mixed, your batter will look thin and a little bubbly, this is normal. Bubbles mean your leavening agents and acidic ingredients are reacting to each other and ready to help your batter rise in the oven.
For more tips on how to bake the perfect cake, check out my post: 10 tips for baking cake
Frosting your cake
I've included my recipe below for whipped chocolate buttercream frosting, which is a fluffy, sweet buttercream frosting. This frosting spreads easily with an offset spatula or knife and crusts when set. For a less sweet option, I'd recommend ermine frosting, also known as boiled milk frosting or flour frosting.
As written, this frosting recipe will frost:
- A 9x13 cake
- A 13x18 cake
- The middle and top of a layer cake with thick layers of frosting (as shown in the photos)
- The middle, top, and sides of a layer cake with a thin layer of frosting
If you'd like thick frosting on all sides of a layer cake, make an additional half batch of frosting. If you'd like to add decorations (like piped rosettes), you may also need additional frosting.
Do not frost a warm cake! Buttercream frosting melts around 90 degrees Fahrenheit. Adding frosting to a hot cake will cause it to melt. Wait until your cake is completely cooled.
Homemade cakes are best served the same day they are baked for best flavor and texture. However, there are solutions if you need to make your cake a few days (or weeks) ahead of time.
Room temperature - Frosted cake can be stored in a tightly sealed container (or wrapped well with foil) at room temperature for 2-3 days, but will begin to dry out over time.
Frozen - Cake and frosting freezes and thaws beautifully, maintaining its original texture and moisture just like the day it was baked. Unfrosted or frosted cake can be frozen for up to two months. To store a frosted cake, first freeze for an hour, unwrapped, until firm. Gently wrap in plastic and store in a tightly sealed container for up to 2 months. Thaw your cake in the refrigerator overnight, then bring to room temperature 30-60 minutes before serving.
Refrigerated - I do not recommend this option unless you live in a hot or tropical climate. Refrigerators are a low humidity environment and dry out cake faster than storing at room temperature or freezing. Unfrosted or frosted cake can be refrigerated for 3 to 4 days if needed. Wrap unfrosted cake in plastic and store in a sealed container. Bring to room temperature 30-60 minutes before serving.
Hot climates - Buttercream frosting should not sit out in the sun or a hot room for extended periods of time because it melts at about 90 degrees Fahrenheit. If it's summertime or you live in a tropical climate, you may need to store your buttercream frosted cake in the refrigerator until 30 minutes before serving to prevent melting.
How to prevent dry cake
No one wants to go through the steps of baking a cake only for it to turn out dry! These are my favorite tips to ensure your cake bakes up moist and tender. For a full list of my favorite cake tips and tricks, check out this post: 10 tips for baking cake
- Do not substitute ingredients. The fats and sugar (granulated sugar, eggs, buttermilk, and vegetable oil) in this recipe help keep your cake moist. Substituting those ingredients changes the texture and moisture in your cake.
- Properly measure your flour. Too much flour can cause a cake to turn out dry. Either use a kitchen scale to weigh your flour (this is what I do and recommend), or spoon the flour into your measuring cup and level off with a knife. Scooping with the measuring cup directly from a bin of flour compacts it into the cup, adding up to 25% extra flour to the recipe.
- Do not overbake your cake. If you haven't substituted ingredients, the only other reason your cake will turn out dry is from overbaking.
- Watch your cake, not the time. Ovens are inconsistent and can run hotter or colder than the next oven. The time that worked for me may not work for you. Start checking your cake 5 minutes early for doneness.
- If your oven bakes unevenly, rotate the cake pan(s) halfway through baking.
- Ways to check for doneness: 1. Does your cake jiggle a lot when you move the pan? It's not done yet. 2. Gently press on the top of the cake with your finger. If the cake pops back up immediately, it's done. If an indentation is left, your cake needs more time. 3. Poke a toothpick into the center of your cake - if it comes out clean or with dry crumbs, your cake is done.
- Use an aluminum pan instead of glass. Glass is an insulator, which means it takes longer to heat up in the oven, taking longer to bake your cake. This can cause the edges to dry out while waiting for the center to finish baking. While this is not always the case, I suggest using metal for the most consistent results (especially for beginner bakers).
- This is a baker's secret (optional, but effective!) - brush simple syrup over your cake before frosting. A layer of simple syrup helps keep the cake moist for longer. Simple syrup is a 1:1 ratio of water and granulated sugar, brought to a boil on the stove top until dissolved, then cooled to room temperature. I'd suggest about ¼ cup or more for this size cake.
Chocolate Sheet Cake
- 1 ¾ cups (210 g) all-purpose flour
- ¾ cup (63 g) natural cocoa powder
- 2 teaspoons baking soda
- 1 teaspoon baking powder
- ½ teaspoon salt
- 1 ¾ cups (345 g) granulated sugar
- 3 large eggs, room temperature
- 1 cup (227 g) buttermilk
- 1 cup (226 g) warm water
- ½ cup (100 g) vegetable oil
- 2 teaspoons vanilla extract
Whipped chocolate buttercream frosting
- 1 cup (227 g) unsalted butter, room temperature
- 3 cups (342 g) confectioner's sugar
- ½ cup (42 g) natural cocoa powder
- ⅓ cup (75 g) heavy cream, cold
- 2 teaspoons vanilla extract
- ¼ teaspoon salt
- Preheat oven to 350 degrees Fahrenheit. Generously grease a 9x13 or 13x18 inch baking pan and set aside. Or, grease two 9-inch round cake pans, line the bottoms with parchment circles, and set aside.
- In a bowl, add flour, cocoa powder, baking soda, baking powder, and salt. Sift or whisk to remove clumps. Set aside.
- In a large bowl, add granulated sugar, eggs, buttermilk, warm water, vegetable oil, and vanilla extract. Whisk or stir until evenly incorporated.
- Add half of the dry ingredients to the wet ingredients. Gently stir until just combined. Add remaining dry ingredients and stir until just combined (do not overmix). Batter should look thin and a little bubbly.
- Pour batter into prepared baking pan (or evenly between two round cake pans).
- 9x13 baking pan: 32-38 minutes13x18 half sheet pan: 18-20 minutesTwo 9 inch round cake pans: 26-30 minutesTwo 8 inch round cake pans: 28-34 minutesBake your cake using the time frames above as a reference. To test for doneness, gently press into the center of your cake with a finger. If it bounces back, it's done. If it leaves an indent, the cake needs more time. Or, test with a toothpick - if it comes out with crumbs, it's done.
- Remove cake from oven and allow to cool completely in the pan(s) on a wire cooling rack.
- *As written, frosting covers a 9x13 cake, 13x18 cake, or the middle and top of a 2-layer cake with thick layers (with bare sides). To frost the sides, use thin layers of frosting or make an additional half batch of frosting.
- In a large bowl, add room temperature butter. Using a hand mixer or stand mixer, beat until creamy (about a minute). Gradually add confectioner's sugar and mix slowly until ingredients are fully combined. Then, whip at high speed for about 2-3 minutes, or until light and fluffy.
- Add heavy cream, vanilla extract, and salt. Whip for an additional 2-3 minutes, or until light and fluffy. Add additional heavy cream as needed to reach desired consistency.
- For sheet cakes: Spread frosting in an even layer onto cooled cake. Optionally, add sprinkles before frosting crusts. For layer cakes: Gently flip and remove cakes from their pans. Trim the rounded tops with a serrated knife to make flat layers. Place one layer, top side down, onto a cake stand or serving plate. Top with frosting and spread into an even layer. Add second layer of cake, top side down, and top with another layer of frosting. If frosting the sides, spread remaining frosting onto the sides of the cake.
- Sheet cake can be sliced to serve up to 24 guests.
- Baking is an exact science. I do not recommend substituting any ingredients. The oil, buttermilk, eggs, and sugar keep your cake moist - substituting any of these ingredients can change the texture and make your cake dry.
- Unfrosted or frosted cake will keep in a sealed container at room temperature for 2-3 days, in the refrigerator for 3-4 days, or frozen for up to 2 months. If refrigerating or freezing unfrosted cake layers, wrap tightly in plastic and place in a tightly sealed container. Thaw overnight in the refrigerator, then bring to room temperature for an hour before serving.
- Be sure to check out my 10 tips for baking cake, based on reader comments and questions!