Chocolate Sheet Cake

The BEST Chocolate Sheet Cake I’ve ever had. This BIG chocolate cake is covered in the creamiest chocolate frosting and loads of candy and chocolate. It’s perfect for birthdays, parties and celebrations.

It’s party time  🎉

And I’m bringing the cake. A Chocolate Sheet Cake with lashings of chocolate frosting and LOADS of candy, including Snickers, Twix, Maltesers and M&M’s.

If you’re on the hunt for a cake that feeds a crowd, this is your answer. A giant sour cream chocolate cake that boasts an incredibly light and tender crumb and a boatload of crispy, crunchy candy.

why you will love this recipe

• Soft and tender chocolate cake that stays moist for days
• Extra creamy chocolate frosting
• Easily customisable with your favourite candy
• Feeds a hungry crowd

recipe testing

I’ve been craving a good, old-fashioned, lick-the-spoon-clean chocolate cake for weeks – so here we are. I actually developed this Chocolate Sheet Cake recipe over five years ago, and I can confirm it is still just as good today.

What makes it so special I hear you ask? Well it comes down to two things. Just like my favourite Chocolate Fudge Cake, this cake uses butter – not oil. Butter gives chocolate cake a deliciously rich and fudgy flavour, without any oil after-taste.

And the second is sour cream. YES, full fat sour cream makes this Chocolate Sheet Cake extra tasty, extra soft and extra moist. And it stays that way for days.

And what is a good chocolate cake without a really, really good chocolate frosting? My chocolate buttercream not only has real melted chocolate in it, but it also has the same secret ingredient – sour cream!

Yes we put sour cream in the frosting too. It makes it extra creamy and smooth and helps to balance the sweetness that can sometimes overpower chocolate buttercream. It’s heaven.

Add all your favourite candy and you have the perfect party cake, am I right? 🥳

what you will need

Here’s a snapshot of everything you will need to make this Chocolate Sheet Cake.

• Unsalted butter
• Caster sugar: Or granulated sugar.
• Brown sugar
• Vanilla extract
• Eggs
• Plain flour: Or all purpose flour.
• Cocoa powder: I recommend using an unsweetened, 100% cocoa powder.
• Baking powder
• Baking soda
• Sour cream: Full fat sour cream makes this cake soft and moist. If you don’t have access to sour cream, the next best thing would be full fat Greek yogurt or natural yogurt.

how to make chocolate cake batter

This cake batter is thick, smooth and creamy. You’ll start by creaming the butter and sugars together using an electric mixer. Here’s how to make the cake batter in four simple steps.

1. Use an electric mixer to cream together the butter and sugars.
2. Add vanilla and eggs and mix until combined.
3. Add flour, cocoa, baking powder, baking soda and salt, along with the hot water.
4. Finally, stir through sour cream.

Once your cake is cooked and cooled, it’s time to frost and decorate – the best part. My favourite chocolate frosting and plenty of candy will make this cake complete.

let’s talk about sour cream

Can you put sour cream in cakes? What does it do? Well I’m glad you asked. Just like buttermilk, sour cream helps break down gluten and proteins, creating tender and moist baked goods.

It offers a slight tanginess, balancing sweetness, and the fat content ensures baked goods are extra moist – and stay that way for days.

Don’t have sour cream? Use full fat Greek or natural-style yogurt instead. I often use yogurt in my cakes – like my famous Apple Cake and my Lemon Crumb Cake. It’s something I always have on hand and I find it has a very similar result.

perfect chocolate buttercream

This Chocolate Cake is covered in a beautiful, silky smooth chocolate buttercream. It’s made using real melted chocolate in the frosting, rather than cocoa powder, which makes it extra creamy and full of flavour.

Instead of milk or cream, I also use sour cream for a seriously fluffy frosting. If you don’t have access to sour cream, you can use full fat Greek yogurt or regular milk.

Here are my tips for perfect chocolate buttercream every time.

1. Start with softened butter: To achieve a truly creamy texture, begin with room temperature butter. It shouldn’t be rock hard straight from the fridge, but on the other hand, it shouldn’t be wet or melty. Try the thumb test: when you press your thumb into the butter, it should easily make an indent.
2. Sift your sugar: For a silky smooth buttercream, you must sift your icing sugar – twice even. Getting rid of the lumps now means you’ll be able to effortlessly create a silky frosting, without being tempted to over-beat your buttercream.
3. Ensure your chocolate is melted and smooth: Since we are using real chocolate in the buttercream, it’s important your chocolate is melted and smooth when you add it to your buttercream. Make sure it’s not hot – leave it to cool slightly if it’s hot to the touch.
4. Beat well: Once you have added all your ingredients, don’t be afraid to give your buttercream a good mix on medium-high speed for 30 seconds. Not only will it make sure everything is incorporated but it’ll give you an extra creamy frosting.

Can I make the frosting ahead of time?

Yes! You can make the buttercream and place it in an airtight container in the fridge. When you are ready to frost your cake, leave the buttercream to thaw for 30 minutes or so at room temperature.

Then, add a tablespoon of milk and beat it on a low speed until it’s smooth and creamy again.

candy decorations

To make this Chocolate Sheet Cake extra special, I love to decorate it with plenty of candy. I usually use chopped Snickers and Twix bars, along with Maltesers and M&M’s. But you can use any chocolate or candy you like!

frequently asked questions

more chocolate cakes to love

• Chocolate Olive Oil Cake
• Chocolate Orange Cake
• Chocolate Mud Cake
• Chocolate Fudge Cake

Did you make this recipe? Don’t forget to rate the recipe and leave a comment below. Hungry for more? Join me on Instagram, Facebook, Pinterest and Twitter for more amazing recipe ideas.

Let’s Bake

Chocolate Sheet Cake

Yield Makes 20–24 slices 1x

1x2x3x

★★★★★

5 from 3 reviews

Prep: 60 minutesCook: 35 minutesTotal: 1 hour 35 minutes

Large Chocolate Sheet Cake covered in chocolate frosting and candy. 

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Ingredients

Chocolate cake

• 120 ml (1/2 cup) hot water
• 230 grams (1 cup) unsalted butter, room temperature
• 200 grams (1 cup) caster sugar or granulated sugar
• 90 grams (1/2 cup) brown sugar
• 2 teaspoons vanilla extract
• 3 large eggs, room temperature
• 245 grams (1 and 3/4 cup) plain flour or all purpose flour
• 60 grams (3/4 cup) cocoa powder
• 1 teaspoon baking powder
• 1 teaspoon baking soda
• 1/2 teaspoon salt
• 240 ml (1 cup) full fat sour cream, room temperature

Chocolate frosting

• 115 grams (1/2 cup or 1 stick) unsalted butter, room temperature
• 75 grams (1/2 cups) dark chocolate (50-70% cocoa), roughly chopped
• 250 grams (2 cups) icing sugar or powdered sugar, sifted
• 3 tablespoons full fat sour cream
• 450 grams (3 cups) assorted chocolate and candy pieces, roughly chopped

Instructions

1. Chocolate cake
   Grease a quarter-sized sheet pan (9 x 13 inch / 23 x 33 cm) and line with baking or parchment paper, ensuring two sides of the paper overhang.
2. Preheat oven to 180 C (350 F) standard / 160 C (320 F) fan-forced. Boil the kettle and pour out 1/2 cup water and set aside.
3. In a large mixing bowl, beat butter and sugars with an electric mixer on medium speed for 1-2 minutes or until creamy and combined.
4. Add vanilla and eggs, one at a time, and continue to beat until combined. Take a moment to scrape down the sides of the bowl. 
5. In a separate bowl, sift flour, cocoa powder, baking powder, baking soda and salt and lightly whisk. Add the dry ingredients, along with the hot water and gently mix on low speed.
6. Add sour cream and mix on low speed until cake batter is smooth and creamy. 
7. Pour chocolate batter into your prepared pan and smooth out into one even layer.
8. Bake for approximately 35 minutes or until a skewer inserted into the middle of the cake comes out clean. Leave the cake to cool for about 15 minutes before carefully transferring to a wire rack to cool completely.
9. Chocolate frosting
   Place butter in a large mixing bowl and beat with an electric mixer on medium speed until pale and creamy.
10. Meanwhile, melt chocolate in the microwave, stirring every 20 second, until smooth and set aside to cool slightly.
11. Add half the sugar and the sour cream, and beat on low until the sugar is incorporated. Then, add the remaining sugar and beat on low until mixture is smooth and creamy.
12. Next, add melted chocolate to the buttercream, ensuring the chocolate is still smooth and melted but not warm. Beat on medium speed until chocolate buttercream is smooth and creamy. 
13. Gently cover your cooled cake with chocolate frosting. Then scatter candy pieces on top.

Notes

Cocoa powder: Use unsweetened 100% cocoa powder for this recipe. 

Sour cream: I recommend using full fat sour cream for both the cake and the chocolate frosting. If you don’t have access to sour cream, you can use full fat Greek yogurt instead. 

Dark chocolate: Use a good quality dark chocolate for the frosting, somewhere between 50-70% cocoa. 

Candy: You can use any chocolate or candy you like to decorate this cake. I used M&M’s, Maltesers, Twix bars and Snickers bars.

Make-ahead: You can make the chocolate frosting ahead of time and store it covered in an airtight container in the fridge. When you’re ready to use it, leave it to thaw at room temperature for 30 minutes. Then, add a dash of milk as needed and mix it on low speed using an electric mixer until it becomes smooth and creamy again. 

Storage: Once the cake is frosted, you’ll need to store it in the fridge. I recommend bringing the cake back to room temperature before serving. Alternatively, you can store the cake itself at room temperature in an airtight container and just frost it when you’re ready to serve. 

Cake pan: This recipe will make enough cake batter to make a 9 by 13 inch cake, or you can make a two layer 8-inch cake or a three layer 6-inch cake.  

Nutrition Information

Serving Size: 1 slice Calories: 373 Sugar: 33.9 g Sodium: 148.2 mg Fat: 20.1 g Carbohydrates: 46.4 g Protein: 3.9 g Cholesterol: 62.1 mg

Nutrition information is a guide only.

Author: Jessica HolmesCategory: CakeCuisine: Dessert

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