Chocolate Mousse Cake

I learnt how to make this chocolate mousse cake in my basic training at Le Cordon Bleu and every time I make it everyone loves it! It's so much more than a simple chocolate mousse so it's perfect if you want to show off your baking skills.

I've decorated mine with my signature chocolate ruffles which you can find the tutorial for on my channel and also a step-by-step guide in my book Georgia's Cakes.

Either continue scrolling for the step by step recipe or watch my full YouTube tutorial here!

Do I have to add nuts to the sponge?
I have made this cake before without adding nuts and the sponge ended up sticking to the ring. When I pulled the ring away, there was parts of the surface of the sponge missing and it ruined the outside of the cake. If you wanted to avoid nuts I would recommend placing a strip of baking paper around the sides of the ring before placing the sponge there
My sponge broke when I placed it around the edges of the tin
This can happen when the sponge is slightly overcooked. It's a very delicate, thin sponge so it can over bake very easily. If this happens, try turning your oven down 5-10° and keeping a close eye on it

Do I have to add nuts to the sponge?
I have made this cake before without adding nuts and the sponge ended up sticking to the ring. When I pulled the ring away, there was parts of the surface of the sponge missing and it ruined the outside of the cake. If you wanted to avoid nuts I would recommend placing a strip of baking paper around the sides of the ring before placing the sponge there
My sponge broke when I placed it around the edges of the tin
This can happen when the sponge is slightly overcooked. It's a very delicate, thin sponge so it can over bake very easily. If this happens, try turning your oven down 5-10° and keeping a close eye on it

FAQs and Troubleshooting

As with everything chocolate, the better quality chocolate, the better tasting the cake. I always use a couverture chocolate which also melts easier!
Piping the strip of sponge in diagonal lines not only looks prettier but is easier to maintain the straightness of the strip - Watch my youtube tutorial to see how I pipe the sponge cake onto the mat
Replace the pistachio with other crushed nuts such as walnuts or hazelnuts

As with everything chocolate, the better quality chocolate, the better tasting the cake. I always use a couverture chocolate which also melts easier!
Piping the strip of sponge in diagonal lines not only looks prettier but is easier to maintain the straightness of the strip - Watch my youtube tutorial to see how I pipe the sponge cake onto the mat
Replace the pistachio with other crushed nuts such as walnuts or hazelnuts

As with everything chocolate, the better quality chocolate, the better tasting the cake. I always use a couverture chocolate which also melts easier!
Piping the strip of sponge in diagonal lines not only looks prettier but is easier to maintain the straightness of the strip - Watch my youtube tutorial to see how I pipe the sponge cake onto the mat
Replace the pistachio with other crushed nuts such as walnuts or hazelnuts

Top Tips

Sponge:

Preheat the oven to 165°C/330°F with fan or 185°C/365°F no fan.
In a bowl, sift together the flour and cocoa powder
In a large bowl or stand mixer, whisk the egg whites until frothy, then gradually add half of the sugar until soft peaks form
In separate bowl, whisk the egg yolks with the remaining sugar until fluffy and lighter in colour
Using a spatula, gently fold the whisked egg whites and cocoa and flour mix into the egg yolks in 3-4 stages, starting and finishing with the egg whites
Fold until a smooth batter is formed
Fill a piping bag with the sponge mix and line a baking tray with paper or a silicone mat
Using the cake ring as a guide, pipe the sponge mixture onto a lined baking tray, forming a long strip for the sides of the cake, a circular base for the cake and a smaller circle for the middle of the cake
Sprinkles the crushed pistachios over the strip of sponge cake
Bake for 8-10 minutes until springy to the touch
Allow the sponge to cool, flip the mat or paper and carefully peel it away to remove the sponge and set aside

Mousse:
In a saucepan, heat the first amount of cream (125ml) along with half of the sugar until steaming
In a separate bowl, whisk the egg yolks with the remaining sugar until fluffy
Temper the egg yolks by gradually adding the hot cream mixture, then return everything to the saucepan and cook until thickened
Melt the dark chocolate in a heatproof bowl and combine with the sifted cocoa powder
Gradually add the hot cream mixture to the chocolate in stages and mix together until smooth
Allow to cool completely
Whip the second amount of cream (150ml) until soft peaks form, then fold into the chocolate mixture until fully incorporated

Assembly
Place the cake ring onto a plate or cake board
Trim the strip of sponge using scissors or a knife and line the outside edge of the tin (with the side with the pistachios touching the tin)
Trim the larger circle of sponge so it fits snug inside the base of the tin, against the sponge on the side
Pour in the chocolate cream mix until about half way
Trim the smaller piece of sponge and place it on top of the cream mix
Pour in the remaining cream mix onto until it reaches the top of the sponge on the side
Carefully transfer the cake to the fridge and allow it to set for at least 4-5 hours (or overnight)
Once the cake is set, you can remove the cake ring and decorate the top with chocolate ruffles, shavings or fresh fruit
Mousse cake can last in the fridge for 3-4 days

Method

6-7 inch cake ring
Large bowl or Stand mixer
Sieve
Medium bowl
Whisk
Rubber spatula
Baking tray
Baking paper or silicone mat
Saucepan
Heatproof bowl
Piping bag
Plate or cake board

6-7 inch cake ring
Large bowl or Stand mixer
Sieve
Medium bowl
Whisk
Rubber spatula
Baking tray
Baking paper or silicone mat
Saucepan
Heatproof bowl
Piping bag
Plate or cake board

Equipment

Sponge:

60g egg yolk
30g sugar
90g egg white
60g sugar
75g plain flour
15g cocoa
25g crushed pistachios

Mousse:
125ml double cream
25g egg yolk
25g sugar
25g dark chocolate
15g cocoa powder
150ml double cream

Ingredients

Do I have to add nuts to the sponge?
I have made this cake before without adding nuts and the sponge ended up sticking to the ring. When I pulled the ring away, there was parts of the surface of the sponge missing and it ruined the outside of the cake. If you wanted to avoid nuts I would recommend placing a strip of baking paper around the sides of the ring before placing the sponge there
My sponge broke when I placed it around the edges of the tin
This can happen when the sponge is slightly overcooked. It's a very delicate, thin sponge so it can over bake very easily. If this happens, try turning your oven down 5-10° and keeping a close eye on it

The recipe below makes a 6-7 inch mousse cake

Sponge:

Preheat the oven to 165°C/330°F with fan or 185°C/365°F no fan.
In a bowl, sift together the flour and cocoa powder
In a large bowl or stand mixer, whisk the egg whites until frothy, then gradually add half of the sugar until soft peaks form
In separate bowl, whisk the egg yolks with the remaining sugar until fluffy and lighter in colour
Using a spatula, gently fold the whisked egg whites and cocoa and flour mix into the egg yolks in 3-4 stages, starting and finishing with the egg whites
Fold until a smooth batter is formed
Fill a piping bag with the sponge mix and line a baking tray with paper or a silicone mat
Using the cake ring as a guide, pipe the sponge mixture onto a lined baking tray, forming a long strip for the sides of the cake, a circular base for the cake and a smaller circle for the middle of the cake
Sprinkles the crushed pistachios over the strip of sponge cake
Bake for 8-10 minutes until springy to the touch
Allow the sponge to cool, flip the mat or paper and carefully peel it away to remove the sponge and set aside

Mousse:
In a saucepan, heat the first amount of cream (125ml) along with half of the sugar until steaming
In a separate bowl, whisk the egg yolks with the remaining sugar until fluffy
Temper the egg yolks by gradually adding the hot cream mixture, then return everything to the saucepan and cook until thickened
Melt the dark chocolate in a heatproof bowl and combine with the sifted cocoa powder
Gradually add the hot cream mixture to the chocolate in stages and mix together until smooth
Allow to cool completely
Whip the second amount of cream (150ml) until soft peaks form, then fold into the chocolate mixture until fully incorporated

Assembly
Place the cake ring onto a plate or cake board
Trim the strip of sponge using scissors or a knife and line the outside edge of the tin (with the side with the pistachios touching the tin)
Trim the larger circle of sponge so it fits snug inside the base of the tin, against the sponge on the side
Pour in the chocolate cream mix until about half way
Trim the smaller piece of sponge and place it on top of the cream mix
Pour in the remaining cream mix onto until it reaches the top of the sponge on the side
Carefully transfer the cake to the fridge and allow it to set for at least 4-5 hours (or overnight)
Once the cake is set, you can remove the cake ring and decorate the top with chocolate ruffles, shavings or fresh fruit
Mousse cake can last in the fridge for 3-4 days