Chocolate Cake with Chocolate Mousse

If you are looking for a show stopping celebration cake, this Chocolate Cake with Chocolate Mousse is the answer. Imagine three layers of decadence… A beautifully moist chocolate cake topped with light chocolate mousse and rich chocolate ganache. So good. But that’s not all. We’re going to transform this chocolate layer cake into something truly special. Think delicate stars of creamy whipped cream, a sprinkling of fruity berries and delicate edible flowers. I’ll grab my spoon! 

Like all the best cakes, this Chocolate Cake with Chocolate Mousse looks impressive, but is actually rather simple. In fact, the mousse is even easier than my Classic French Chocolate Mousse! Bear in mind you do need to leave enough time for the individual layers to cool and/or set. However, that makes it the perfect make-ahead dinner party dessert or birthday cake. Plus, when you focus on one layer at a time you will be surprised at how easy it is.

Why you will love this recipe:

• It has the most delicious decadent flavour and texture. Imagine layers of moist chocolate cake, light chocolate mousse and rich chocolate ganache. All topped off with creamy whipped cream and fruity berries.
• It looks impressive but is actually simple. A dream dinner party dessert or celebration cake.
• It is the perfect make-ahead recipe. Ideal for when you want to get organised and avoid last minute stress.

Ingredients:

Full recipe can be found in the printable recipe card at the bottom of the post, just scroll down!

Cocoa powder - make sure you use the unsweetened variety. Definitely not hot chocolate powder!

Boiling water - using boiling water adds depth to the cocoa powder for a more chocolate-y flavour.

Instant coffee - don’t worry, this won’t make this a coffee-flavoured Chocolate Cake with Chocolate Mousse! Adding a hint of coffee to chocolate recipes intensifies the chocolate flavour. I recommend the Nescafe Azera or Lavazza Prontissimo! instant coffee.  

Plain flour - also known as ‘all-purpose’ flour. This helps give the chocolate cake layer structure. 

Baking powder - since we are using plain flour (not self raising), a little baking powder gives the cake a bit of a life.

Bicarbonate of soda - this also helps give the chocolate cake a light, airy texture. We can use it in this recipe since we are including yoghurt (which is acidic).

Caster sugar - this brings sweetness to the chocolate cake layer. It also helps give it a beautifully soft texture.

Salt - this won’t make the Chocolate Cake with Chocolate Mousse taste salty. It balances out the sweetness and heightens the other flavours. I recommend Maldon Salt Flakes. 

Egg - I always use free-range eggs. I also recommend using a large egg stamped with the British Lion mark.

Vegetable oil - this helps create a lighter, more moist, chocolate cake. 

Thick Greek yoghurt - this also helps create the most wonderful texture. Opt for full-fat versions for the best results.

Dark chocolate - the starring ingredient in this chocolate mousse cake! Opt for the best quality you can find, ideally 70%, for the most delicious results. If making this for children you might want to use milk chocolate which is slightly sweeter

Double cream - also known as ‘heavy’ cream. This is used in the mousse and ganache. Take care not to over-whip as it will ruin the texture.

Whipped cream - you can use double or whipping cream to make your whipped cream. Alternatively, for a bit of fun, you can use squirty cream. I like President Aerosol Cream. It has a hint of vanilla which is delicious.

Seasonal berries - I love the combination of sweet fruit and rich chocolate. It is the perfect balance. I like to use whatever is in season. Cherries, raspberries and strawberries are all lovely. If serving to young children, I pit the cherries first.

Edible flowers - these are entirely optional but make a very pretty decoration. You must ensure they are edible and prepared properly.

Substitutions and Variations:

• Caster sugar: you can swap for granulated or golden caster sugar if that is what you have. Alternatively, soft light brown sugar will give a subtle molasses flavour and even more moist texture.
• Oil: you can use any flavourless oil. Sunflower or rapeseed oil would both work well.
• Vanilla: add a couple of drops of vanilla extract or a little vanilla paste to the cream for a subtle vanilla flavour. Avoid vanilla essence as this is synthetic and will give your chocolate mousse cake a synthetic flavour.
• Berries: a sprinkling of plump and juicy berries cuts through the rich dark chocolate. I like strawberries, raspberries or pitted cherries. You can also opt for a fruity berry coulis. Alternatively, Bonne Maman has some delicious compotes which work really well. However, if you are serving it to adults, a spoonful of cherries in Kirsch is very special. Almost like a nod to a Black Forest Gateau.
• Chocolate: I have only ever made this with dark chocolate but if you want to there is no reason you couldn't use milk chocolate. One reader has even reported using Toblerone in the mousse with great success.

Here's how to make Chocolate Cake with Chocolate Mousse:

There are three steps to make this cake, but I promise each one is very simple. I’ve broken it down here, so let me show you what you do.

Step 1 - To Make The Cake:

ONE: Preheat the oven to 190C / 170C Fan. In a small bowl, whisk together the cocoa powder, boiling water and instant coffee until combined and glossy. Set aside.

TWO: In a large bowl, sift in the flour, baking powder, bicarbonate of soda, caster sugar and salt.

THREE: Add the egg, yoghurt and the vegetable oil. Give it all a good mix to combine, then stir in the chocolate-coffee mix until you have a smooth, chocolatey cake batter.

FOUR: Pour the batter into the prepared cake tin and bake for about 20-25 minutes - or until it springs back to touch. 

Step 2 - To Make The Mousse:

This makes a thick mousse so that it stands firmly in the cake. You can try my French Chocolate Mousse recipe for something more traditional, a pudding in its own right.

FIVE: Melt the chocolate. I normally do this in the microwave but you could do it in a heatproof bowl over a pan of barely simmering water. Stir until it's melted and smooth.
Whisk the double cream either in a stand mixer or using an electric whisk. Whisk until you get soft peaks. Do not over whip.

SIX: Stir the cream into the chocolate until it's all well mixed.

SEVEN: Clean and re-prep the cake tin with non-stick paper (extending 2.5cm/1-inch above the tin), fill with chocolate mousse, spread evenly, cover with cling film, and chill in the fridge for 4 hours or overnight.

EIGHT: Once the mousse has set, remove from the tin, peel off the baking parchment and set onto a flat serving plate.

And Finally, Make The Ganache:

NINE: To make the chocolate ganache: Heat cream over low-medium heat until simmering, then pour over chopped chocolate in a bowl and let it melt together.

TEN: Pour the ganache over the centre of the cake, then use the back of a spoon or palette knife to gently spread it over the top, allowing it to drip down the sides. 

Cooking Tips:

• Glossy ganache: for a super glossy ganache layer, add a drizzle of golden syrup (about 2 tsp). It will also add a little extra sweetness. 
• Whipped cream: take care to whip the cream just to soft peaks for the mousse and decoration. If you over whip, it will split and you will eventually get something akin to butter.

Frequently Asked Questions

Other recipes you might enjoy:

If you like the sound of this Chocolate Cake with Chocolate Mousse, try my Classic French Chocolate Mousse. It uses just 3 ingredients and tastes absolutely incredible! However, if you want a celebration cake, my Moelleux au Chocolat must not be missed. nor my Jaffa Cake Cake. Or for a mix of chocolate and coffee, try my Tiramisu Cake, made with Panettone. For something festive, try my Panettone Tiramisu or my Buche de Noel Yule Log.

Made this recipe and loved it?

I would love love LOVE if you could leave a review in the comments…  I love hearing what you thought, any changes you made, the stories behind what made you try my recipes. Also, if you share a photo on Instagram, please tag me @desertislanddishes, it makes my day to see you making my creations!

Chocolate Cake with Chocolate Mousse

Print Recipe

Pin Recipe

5 Stars 4 Stars 3 Stars 2 Stars 1 Star

5 from 2 reviews

This Chocolate Cake with Chocolate Mousse is super decadent and delicious. Imagine layers of moist chocolate cake, creamy chocolate mousse and rich chocolate ganache. It’s a real showstopper. 

• Author: Margie
• Prep Time: 30 minutes
• Chill Time: Minimum of 4 hours
• Cook Time: 25 minutes
• Total Time: 55 minutes + chill time
• Yield: Serves 8 - 10 1x
• Category: Dessert and Cakes
• Method: Baking
• Cuisine: Global
• Diet: Vegetarian

Ingredients

Scale 1x2x3x

For the chocolate cake:

• 25g cocoa powder
• 60ml boiling water
• 5g good-quality instant coffee 
• 125g plain flour
• 1 tsp baking powder
• ½ tsp bicarbonate of soda
• 160g caster sugar
• ½ tsp flaky sea salt
• 1 large egg
• 65 ml vegetable oil
• 120ml thick Greek yoghurt

For the chocolate mousse:

• 300g good-quality dark chocolate, chopped (I recommend 70%)
• 450ml double cream 

For the chocolate ganache:

• 180g good-quality dark chocolate, finely chopped (I recommend 70%)
• 180 ml double cream
• Pinch of flaky sea salt

To serve: (optional)

• Whipped cream
• Seasonal berries
• Edible flowers

Cook Mode Prevent your screen from going dark

Instructions

1. Preheat the oven to 190C / 170C Fan. Grease and line a 23cm (9-inch) round loose-based cake tin with non-stick baking paper. Set aside.
2. In a small bowl, whisk together the cocoa powder, boiling water and instant coffee until combined and glossy. Set aside.
3. In a large bowl, sift in the flour, baking powder, bicarbonate of soda, caster sugar and salt.
4. Add the egg, yoghurt and the vegetable oil. Give it all a good mix to combine, then stir in the chocolate-coffee mix until you have a smooth, chocolatey cake batter.
5. Pour the batter into the prepared cake tin and bake for about 20-25 minutes - or until it springs back to touch. 
6. Set aside to cool in the tins for 5 minutes before turning out onto a rack and leaving to finish cooling completely.
7. Once the cake has cooled, prepare your cake tin once again. Clean well before greasing and lining with a non-stick baking paper - this time, ensure that the lining on the inside comes at least 2.5cm (1-inch) above the top of the cake tin (a bit like a collar). This is just an insurance policy to ensure you have enough room for the chocolate mousse. Gently slide the cooled cake back into the tin.
8. Next, make the chocolate mousse: place the chopped chocolate into a heat-proof bowl. Set over a pan of barely simmering water, ensuring the bottom of the bowl doesn’t come into contact with the water (or the chocolate will overheat) and allow it to slowly melt, stirring often until smooth. Alternatively, pop into a microwave-safe bowl and melt in 20 second bursts, stirring between each. This is the quickest method but you have to watch closely and ensure it doesn’t overheat or it will burn and you will have to start again. Once melted, set aside to cool slightly.
9. Meanwhile, whisk the cream until you have soft peaks - take care not to over whisk. Gently fold in the cooled melted chocolate until no streaks remain. 
10. Spoon the chocolate mousse mix over the cake and spread in a smooth, even layer. Cover with cling film and chill in the fridge for at least 4 hours — or overnight — until set.
11. Once the mousse has set, remove from the tin, peel off the baking parchment and set onto a flat serving plate.
12. Next, make the chocolate ganache: pop the chopped chocolate into a heat-proof bowl and set aside. Pour the cream into a small saucepan and set over a low-medium heat. Slowly bring to a simmer, then remove from the heat and pour over the chopped chocolate. Allow to sit for 2 minutes before gently stirring to encourage it to melt. Continue to stir until glossy and smooth.
13. Pour the ganache over the centre of the cake, then use the back of a spoon or palette knife  to gently spread it over the top, allowing it to drip down the sides. 
14. Chill in the fridge for 30 minutes to allow the ganache to set. 
15. To serve: either serve slices as is, or top with piped whipped cream (I use a star nozzle), seasonal berries and edible flowers. You can simply spoon the whipped cream if you prefer not to pipe.

Notes

• Serving suggestions: this decadent Chocolate Cake with Chocolate Mousse is perfect on its own. However, it is made even more special with some softly whipped cream. Vanilla ice cream is also delicious. Seasonal berries are always delicious with anything chocolatey - raspberries, cherries and strawberries are my favourites. You can also opt for a fruit compote or coulis. 
• Make ahead: this Chocolate Cake with Chocolate Mousse is a great make ahead dessert recipe. I like to make the chocolate cake and chocolate mousse layer the night before so I have no last minute stresses on the day. 
• To Store: Once made, this should be kept in the fridge because of the mousse and ganache. Cover well and it should keep for 2 days.
• To freeze: You can make the cake part ahead of time, and freeze it - wrap it well to avoid freezer burn and then defrost when you want it. Don't freeze the mousse or ganache.