This blueberry chocolate cake is truly incredible: intensely chocolatey and rich in flavour, with a soft, fluffy and moist texture, then it’s all topped off with the most amazingly creamy and silky smooth blueberry frosting.
To keep things super simple, it’s made into a chocolate snack cake style – single layer, square tin and perfectly snackable. It’s seriously quick and easy. And I’m not even joking when I say quick. The chocolate cake comes together in one bowl and there’s no need for creaming butter and sugar, saving loads of time.
The blueberry frosting is the stuff of blueberry dreams. It’s full of natural blueberry flavour – no artificial flavours or extracts and no artificial colours. It’s also creamy, silky smooth and just perfectly sweet. Similar to making a regular buttercream, this one is an ermine blueberry frosting (ermine is a milk & flour base frosting) and it is legit smooth! No graininess whatsoever. You’re going to love it.
If you love this, you’ll also love this black magic cake or try these Chocolate mini cakes.
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Ingredients you’ll need
Here are the ingredients you’ll need for this blueberry and chocolate cake along with any substitutions.
Jump to the recipe for full ingredients and instructions.
- Flour: Just plain flour / all purpose flour and you’ll use this in both the cake and the frosting (trust me you don’t taste flour in the frosting but it gives a sensational smooth texture).
- Cocoa: You just need regular unsweeted cocoa powder though you can also use dutch-process cocoa powder.
- Sugar: You’ll need granulated sugar or caster sugar (superfine sugar) for both the cake and frosting. I prefer the caster sugar as it will dissolve quicker in the frosting.
- Baking powder & baking soda: This cake uses a combination of both baking powder and baking soda (bicarbonate of soda). This combo gives it the perfect lift and texture.
- Eggs: The recipe uses one whole egg and a yolk.
- Buttermilk: Buttermilk is wonderful for creating tender cakes and also activates the baking soda. You can also use sour cream.
- Vegetable oil: Just a neutral flavoured vegetable oil. This will add moisture and tenderness to the cake.
- Vanilla extract: Make sure to use extract, not essence. The latter is a synthetic flavouring.
- Blueberries: I use frozen blueberries often for this. They have great flavour, are available all year round and are affordable.
- Milk: Use regular full fat milk for the frosting.
- Butter: Stick to unsalted butter and make sure it’s softened.
How to make blueberry chocolate cake (step-by-step)
Chocolate and blueberry is a wonderful flavour combination and this chocolate blueberry cake is two deliciously simple layers that taste unbelievable together. Being just a single layer cake makes it incredibly easy too.
The chocolate cake batter can be made with just a handheld beater but the frosting is best made with a stand mixer with paddle attachment.
Jump to the recipe for full ingredients and instructions.
Start the blueberry frosting
Starting with the blueberry puree and pudding mixture for the frosting gives it ample time to cool before adding it to your frosting.
- Cook the blueberries: Add blueberries and lemon juice to a pan and cook over medium heat until they’ve released lots of juice. Use a potato masher to crush the blueberries so you can extract all the juice.
- Strain: Strain the blueberry juice into bowl making sure to press as much liquid through as you can.
- Reduce: Now reduce the blueberry juice to the pan and cook to reduce it right down to ⅓ of a cup. Set aside 1 tablespoon – that’s for your swirling later.
- Turn it into a “pudding” base: Add flour, milk and sugar to the pan with the reduced blueberry puree. Cook it until it’s really thick and dark. Set aside to cool.
Make the chocolate cake
- Dry ingredients: Mix the dry ingredients in a large bowl.
- Wet ingredients: Add the wet ingredients to the bowl and use a hand mixer to mix them together.
- Bake: Pour it into a lined 8 inch square cake pan and bake for 35 minutes or so, just until a toothpick comes out with a few sticky crumbs but no wet batter.
- Turn it out: The cake bakes up fairly flat on top but I like to take an extra step to make sure. Place a wire rack upside down on top of the cake tin and flip it over. Lift the cake tin off and let the cake cool like that. This will give you a nice flat top so you get perfect layers of cake and frosting.
Back to the frosting
- Butter and sugar: Beat together butter and sugar like you would for a regular buttercream, though this time you’re using granulated or caster sugar (the latter is my preference). Don’t worry – it will dissolve completely and you won’t have a grainy buttercream.
- Add the blueberry pudding: Now add that blueberry pudding mix you made earlier, 1 tablespoon at a time until it’s all combined. Beat it for a good 5-7 minutes until it’s thick and whipped then beat in the vanilla and it’s ready.
What is ermine frosting?
This blueberry chocolate cake is topped with the most dreamy blueberry frosting: Ermine frosting / buttercream is amazing stuff. It’s not as overwhelmingly sweet as a regular buttercream and it’s a smooth as silk.
It starts out a bit strange by cooking flour and milk (and in this case blueberry puree) into a very thick pudding-like texture. We also use granulated sugar instead of icing sugar (powdered sugar). I like to use caster sugar to be super safe but it always completely dissolves either way. No grittiness that you get in powdered sugar buttercreams.
Keep in mind, it can tend to have a split look as it’s beating up but it will end up completely smooth, just be patient. It’s best used immediately though, so don’t make it until you know you’re ready to spread it on the cake. Once it’s on the cake, it keeps fine, just like any other buttercream.
Tips and tricks
- Weigh your ingredients: Always use a kitchen scale to weigh ingredients like flour and sugar. You’ll get the most accurate result this way, plus there’s less to wash up as you can measure directly into the bowl.
- All ovens vary: This is so important as what takes 35 minutes in my oven, may take 33 or 37 in yours. Many oven thermostats are out of whack and I always recommend keeping a separate oven thermometer inside your oven to keep an eye on the temperature.
- If using fresh blueberries, take care to wash and pat them dry first.
Variations
Chocolate and berries always go well together so maybe instead of making a blueberry chocolate cake you could swap them for raspberries, blackberries or even strawberries.
If you don’t feel like making the ermine buttercream, you could make a cream cheese frosting.
This cake will layer well up to 2 layers. I would do just 1 ½ times the recipe if using 2 round 8 inch cake pans though.
You could go a step further and top this cake with a decadent dark chocolate ganache.
Yield and storage
This blueberry chocolate cake will keep well in the fridge for 4-5 days in an airtight container. You can freeze it as well – slice it first, then freeze in an airtight container or in freezer bags.
More chocolate cake recipes you’ll love
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Ingredients
FOR THE CHOCOLATE CAKE
- 165 g plain flour (all purpose flour) (1 ¼ cups)
- 55 g unsweetened cocoa powder
- 300 g granulated white sugar (1 ½ cups/10 ½oz)
- 1 ¼ teaspoons baking soda (bicarb soda)
- ¼ teaspoon baking powder
- ¼ teaspoon salt
- 1 large egg
- 1 egg yolk
- ¾ cup buttermilk (180ml)
- 2 teaspoons instant coffee dissolved in ½ cup boiling water)
- ⅓ cup vegetable oil (like canola oil or light flavoured olive oil) (80ml)
- 1 teaspoon vanilla extract
BEST EVER BLUEBERRY FROSTING
- 2 ½ cups frozen blueberries (380g/13 ½oz)
- 2 tablespoons lemon juice (notes 1)
- ⅔ cup whole milk
- ¼ cup plain flour (all-purp flour)
- ¾ cup caster sugar (superfine sugar) (150g/5.3oz)
- 170 g unsalted butter, softened (6oz)
- 1 teaspoon vanilla extract (notes 1)
- Pinch salt
- Blueberries for topping
For best results, always weigh ingredients where a weight is provided
Instructions
- START THE FROSTING:Place the frozen blueberries and lemon juice into a medium saucepan and cook until you see a lot of juice in the bottom.
- Crush the blueberries with a potato masher well, then strain into a bowl. Press through as much liquid as possible and discard any pulp. Return the juice to the pan over high heat and bring to a boil, stirring from time to time until you have about ⅓ of a cup of blueberry sauce.
- Set aside 1 tablespoon of the blueberry sauce.
- Off the heat add flour, milk and ½ the sugar to the pan and whisk until smooth.
- Return to medium heat and stir with a spatula constantly until it gets very thick (like a pudding or thick custard).
- Transfer the mixture to a bowl and cover with plastic wrap pressed to the surface. Cool this mix to room temperature (notes)
- FOR THE CHOCOLATE CAKE:Preheat the oven to 180C (160C fan) / 350F. Line an 8 inch square pan with baking paper.
- In a large mixing bowl, sift the flour and cocoa together, then add the sugar, baking soda, baking powder and salt and whisk to combine well.
- Make a well in the centre of the flour mixture and add all of the wet ingredients – egg, buttermilk, oil, vanilla, coffee.
- Use a handheld beater and mix on low for 30 seconds.
- Pour the cake batter evenly into the prepared baking pan. Place in the oven and cook for around 35 minutes or until a toothpick inserted in the centre, comes out with just a crumb or two.
- Remove from oven and immediately place a wire rack upside down on top of the cake. Flip the whole lot over and remove the cake pan. Leave it to cool. This will flatten any dome on top. Once cool remove the baking paper and flip it back over, using the serving dish. Make sure the cake is completely cool before frosting.
- BACK TO THE FROSTING:Beat together the butter and remaining sugar until really creamy. About 5 minutes. Scrape down the bowl a few times through the process.
- Add the cooled blueberry/milk mixture a spoonful at a time, beating on medium until each spoonful is incorporated before adding the next..
- Once the paste has all been added, mix on medium-high for another 5-7 minutes. If it looks like it separates, don’t worry, just keep on beating. It will all come together into a beautiful, almost whipped cream looking frosting.
- Once the frosting looks whipped and light (and not split), add the vanilla. Beat on low just to incorporate then stop.
- Spread over the cooled cake. Add a dash of water to the leftover blueberry puree then use a spoon to dollop little dots over the top of the cake. Swirl through them using a knife.
- Please take a moment to leave a comment & rating. It's appreciated and so helpful.
Notes
- Tablespoons: I use a standard Australian 20ml tablespoon (equal to 4 teaspoons). Check yours before measuring.
- For best results, you should always weigh ingredients like flour and sugar. Kitchen scales are relatively cheap but if you can’t weigh the ingredients, use the spoon and level method (don’t scoop).
- All ovens vary. Check for doneness at least 3 minutes before the recipe suggests.
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2 Comments on “Blueberry Chocolate Cake”
This cake was moist and delicious and the frosting was another level. Well done and Thanks Marie
It’s one of my favourite cakes, Kim. I’m so happy you love it too 🙂