Project Chocolate-Hazelnut & Salted Caramel Mousse Cake

Project Chocolate-Hazelnut & Salted Caramel Mousse Cake

The idea for this cake materialized the night before the boyfriend’s birthday celebration after having spent countless nights before thinking up possible birthday cakes to make. Never have I spent so much time thinking about a cake as much as this, but with the boyfriend being a super critical cake-eater (the cake cannot be too sweet, not too rich, yet not too light, not too much cream etc) and with me wanting to make this cake special (to distinguish a birthday cake from any other usual cake I bake on my whims and fancies), my head whirled with options, imagining how the flavours would work, thinking if the ingredients involved in certain recipe sounded too sweet, how to ensure that the cake didn’t end up too rich, yet rich enough for his liking.

The brainstorming for this cake began a few weeks ago, with the idea to bake him a speculoos cheesecake, as he was still mad about that wonderful biscuit/spread from our recent trip to Brussels, or a passionfruit cheesecake as it married his favourite flavour with his favourite type of cake. I did a trial run for both of them in my kitchen and they were a success!


My trial-run of salted caramel cheesecake with speculoos crust and speculoos drizzle.

However, I suddenly remembered that one of his housemates didn’t eat cheese and since this cake was meant for everyone to celebrate the boyfriend’s birthday with him, cheesecakes were thus not a viable option (I made it for the dessert part of his birthday three-course meal instead). I then moved on to the idea of a black forest cake, something with chocolate (because everyone loves chocolate), only to realize that some of his housemates didn’t like black forest cakes either.

My super rich chocolate cake with peanut butter mousse.

My super rich chocolate cake with peanut butter mousse.

I then remembered the boyfriend saying something about how peanut butter chocolate cakes can be quite delicious. I hadn’t had one before, so I got down in my own kitchen and made a chocolate and peanut butter mousse cake to see how it went. Chocolatey it was, and peanut butter overload was an understatement. Way too rich I thought. Idea scraped.

So I arrived in Coventry two days before his birthday, after a few weeks of trial baking and scraped ideas with no clear plan of what the cake would be. Somewhere in between, I had settled on a combination of hazelnut and chocolate but I wanted to add a textural element to the cake, something with a crunch to break the otherwise continuous medley of soft sponge and soft mousse. Taking my chance to include speculoos in the cake, I decided on a speculoos crumb base. And then somehow, out of the blue, I thought a salted caramel mousse would complement that crust pretty well, and it might just go well with the hazelnut and chocolate. It was quite a risk, combining so many different elements into a cake. It sounded like it could work, but you never know until it’s been made. Well, I took the risk and ran with it, and was really happy with the result! The cake had a nice medley of flavours that were not too sweet yet satisfying, starting with the richer chocolate and hazelnut part at the top and ending with a lighter salted caramel finish with that nice speculoos crunch at the end. If you are a choc-hazelnut (read nutella) purist, you might be better off replacing the salted caramel mousse with another layer of choc-hazelnut mousse and you’ll have a really rich choc-hazelnut mousse cake!


Choc-hazelnut and salted caramel mousse cake recipe:

First thing I did was to make the two different mousses, as they need time to set in the fridge. This cake is a lot of work. I’m not going to lie. Here is a quick overview of what had to be done:

  1. Choc-hazelnut mousse
  2. Salted caramel mousse
  3. Speculoos crumb crust
  4. 2 layers of chocolate sponge
  5. Chocolate ganache
  6. Chocolate meringues

Choc-hazelnut mousse


  • 1 cup heavy cream
  • 1/4 teaspoon instant coffee granules
  • 1/2 cup nutella


1. Dissolve instant coffee granules in the heavy cream by stirring thoroughly (takes around 5-7 minutes)/

2. Add in the nutella and beat with an electric mixer on medium speed until soft peaks form (should take around 2-3 minutes).

3. Place the mousse in the fridge and chill for at least 4 hours. The mousse may appear very loose at this point, but it will firm up when chilled.

Salted-caramel mousse (slightly trickier):


  • 1¼ tsp powdered gelatin/2 sheets of gelatine leaves (I used gelatine leaves, as I find that they tend to be a lot more consistent and reliable in setting the mixture)
  • 8 tbsp cool water
  • 220g sugar
  • 2 and 3/4  cups double cream, divided
  • 1 tbsp of vanilla paste/essence
  • 3 tsp rock sea salt or to taste (I used around 5 tsp. went a little trigger happy there because the boy likes the caramel to actually be salty)


1. Sprinkle powdered gelatine on cold water for around 5 minutes. If using gelatine leaves, soak in cold water for around 5 minutes.

2. Mix sugar and 6 tbsp of water in a sauce pan (stir well at this point, before you put it on the heat).

3. Place the sauce pan over low to medium heat until it begins to turn into a rich caramel colour (takes 8-10 minutes). Remove from heat and let it cool without stirring the mixture. The mixture should darken slightly. Also, do not stir the mixture once the pan is on the heat as this would cause the sugar to re-crystallize and ruin the caramel. If you find that the mixture is re-crystallizing, swirl the pan around gently and this will allow the re-crystallized sugar to mix and melt back into the mixture. Whatever you do, DO NOT STIR with a spoon or whatever tool you have.

4. Slowly whisk in 3/4 cup of double cream into the caramel mixture. The caramel will bubble add as you add the cream but keep on whisking and it will settle down. Set aside and allow it to cool.

5. Whip the remaining 2 cups of double cream with the vanilla until soft peaks are formed.

6. Whisk powdered gelatin into the warm caramel. If using gelatine leaves, wring the sheets and stir it into the warm caramel to let it dissolve.

7. Add in the salt and stir to dissolve.

8. Gently fold the caramel mixture into the double cream.

9. Place in a 20cm (diameter) sandwich tin and allow it to set in the fridge for around 4 hours.

Speculoos crust:


  • Approximately 20 pieces of speculoos biscuits
  • 80g butter


1. Melt 80g of butter (in the microwave)

2. Crush the speculoos biscuits using a rolling pin until fine like breadcrumbs.

3. Stir in the melted butter and press the crumbs into a 20cm springform pan or a 20cm silicon baking tray (something that allows you to remove the crust easily after it has set).

4. Put it into the refrigerator to allow it to freeze up (for minimally 30 minutes)

Chocolate Sponge:


  • 2 eggs, room temperature
  • 60g caster sugar
  • 50g cake flour
  • 10g cocoa powder
  • 20g unsalted butter (melted and cooled)
  • 1 tbsp caster sugar
  • 1 teaspoon brandy
  • 3 tbsp of boiling water


1. Measure out all the ingredients to begin with as the faster you work with the batter, the better the results.

2.Preheat the oven to 170 deg C and line 2 20cm diameter sandwich trays with parchment paper.

3. Beat eggs and caster sugar over a bain-marie (hot water bath) using an electric mixer until the mixture warms up. This allows the sugar to dissolve. The mixture should be warm to touch, but not scalding hot (you should be able to dip your finger into the mixture comfortably).

4. Remove the mixture from the bain-marie and continue beating with the electric mixer until the mixture has tripled in volume and has turned almost white. When you notice that the mixture has tripled in volume and is of a very pale shade, turn the mixer down to its lowest setting to beat for 1-2 minutes to set the texture of the mixture.

5. Sift cake flour and cocoa powder together into a separate bowl (I do it twice for good measure)

6. Add the flour mixture to the egg mixture a little at a time (in 3 stages), using a wire whisk to cut through the mixture (be gentle!). Do not beat at this stage, as you do not want the mixture to collapse.

7. Sprinkle the cooled melted butter over the mixture and fold in gently using a spatula.

8. Pour the batter from a height into the prepared sandwich tins, dividing them equally.

9. Lift the tins and drop it on the table top to eliminate air bubbles.

10. Bake for 15 minutes.

11. Meanwhile, make the cake syrup by dissolving 1 tbsp of caster sugar in 3 tbsp of hot water. Add brandy to taste. The cake syrup can be applied to the sponges before assembling the cake to keep it moist.

12. Remove the tins from the oven and turn the cakes onto a cooling rack. Allow them to cool to room temperature with the pan covering it.

Chocolate Meringue:


  • 2 egg whites at room temperature
  • 55g caster sugar
  • 45g icing sugar
  • 10g cocoa powder


1. Pre-heat oven to fan 100 deg C or 110 deg C for a conventional oven.

2. Line 2 baking trays with parchment paper.

3. Beat the 2 egg whites in a clean mixing bowl on medium speed (using an electric mixer) until light a fluffy, where stiff peaks are formed.

4. Increase the speed of the electric mixer and add in the caster sugar one dessert spoon at a time. Beat for 3-5 seconds after each addition. When ready, the mixture should be thick and glossy.

5. Combine icing sugar and cocoa powder in a separate bowl and sift one third of it into the mixture. Fold in gently using a rubber spatula. Once combined, sift in another third of the cocoa powder and icing sugar and fold it in. Repeat until all the icing sugar and cocoa powder have been folded in. The mixture should now be smooth and billowy.

6. Spoon mixture into a piping bag and pipe the meringues into little drops on the baking trays.

7. Bake in the oven for 1.5-2 hours until the meringue sound crisp when tapped underneath and are a pale brown colour.


Chocolate Ganache:


  • 100g dark chocolate
  • 140ml double cream
  • 1 tbsp golden caster sugar (optional, i left it out as I was trying to cut down on the sweetness of the whole cake)


  • Break chocolate into small pieces and set aside in a large bowl
  • Heat double cream in a sauce pan until almost boiling. Take it off the heat and pour it into the bowl with the chocolate, stirring until all the chocolate has melted.
  • Allow the ganache to cool slightly before applying it to the cake.

Assembling the cake:

Now now, the fun part of putting it all together and ending up with something looking like this:


1. Release speculoos crust from the tray and set it on a cake board/big plate.

2. Run a palette knife/butter knife around the rim of the sandwich tin with the salted caramel mousse and choc-hazelnut mousse. Turn the sandwich tin with the salted caramel mousse onto the speculoos crust. Tap the tin all around to release the mousse from the tin. Peal away the layer of parchment paper on the mousse.

3. Brush the sponge cakes with cake syrup. Place one layer of sponge on the salted caramel mousse.

4. Release the choc-hazelnut mousse on the first layer of sponge and sandwich it with the second layer of sponge.

5. Spoon all of the chocolate ganache onto the middle of the surface of the cake and spread it out in smooth circular motions. Let excess ganache fall over the sides, placing your palette/butter knife vertically, run it round the circumference of the cake, spreading the ganache around.

6. Top the cake with raspberries and meringues!

7. And no cutting into it just yet. Put it back into the fridge and allow it to set for at least half an hour!


Thankfully, we were meant to have the celebration at night, and thus I had no choice but to allow the cake to set in the fridge for a couple of hours (I would most probably have cut into it right away to have a taste of it altogether otherwise…patience is not really a virtue I possess), resulting in nice, distinct layers when we sliced into it eventually.


Before anyone embarks on this recipe, or rather, series of recipes, be warned that making this cake is unbelievably time consuming and you will probably need half the day free to get this cake up properly (or do some components on one day, and finish up the rest on the second). However, it is pretty damn delicious (think smooth rich flavours of chocolate, hazelnuts, salted caramel, speculoos, all amalgamating in one spoonful…ahhhhh) and worthy of any special occasion!

And to my dear boy to whom this cake is dedicated to, happy 23rd. You always ask me why I make birthdays such a big deal and despite my jokes about how its an opportunity for me to spam my face with cakes and good food, its ultimately about celebrating you, celebrating your life, who you’ve become over the years, who you are to me and everybody else. Every day I thank God for bringing you into the world and into my life and your celebrating the day you were born is probably the most natural thing to do. Thanks for finding your way into my life on MSN a couple of years ago (HAHA), for becoming my best friend, my ultimate partner-in-crime/bullshitting partner, my big spoon (in advance), my biggest supporter, my prayer partner, my soul-mate. You will always have that very special place in my heart. ILY <3