Ho ho ho, welcome to the Christmas weekend! I hope you’ve started to decompress from all the work stresses and started enjoying the looking forward to Christmas (for me it’s probably the best part) bit. I am signing off with a magnificent vegan chocolate mousse cake that will make all chocolate lovers, vegan or not, very happy indeed. That’s a promise.
This vegan chocolate mousse cake isn’t actually that hard to make and tastes divine. If you start on it tomorrow afternoon, it will be ready to wheel in by Christmas Day or, if you are a continental like me, start tonight and watch it getting demolished on Christmas Eve’s. Easy peasy.
This cake is perfect for anyone who is scared of making pastry as the base of this vegan chocolate mousse cake is a layer of delightfully fudgy and super chocolatey brownies. They come together really quickly and other than folding – combining ingredients slowly and gently, using a folding motion – no other pastry skills are needed here. The mousse in this vegan chocolate mousse is a little more advanced, but as long as you don’t rush things and follow my instructions, it will come out well. I promise.
This cake is decadent, rich and super chocolatey and it will storm, I am sure. While I decorated my cake with a cloud of Italian meringue, I would not recommend doing the same as this caused problems, which I did not realise until I came to cut the cake. The moisture in the meringue and the act of torching it with a chef’s torch weakened the mousse and made it impossible for me to cut a neat slice 🙁 . Instead, I suggest a thin sprinkling of cocoa powder on top – as is traditional for a tiramisu – and maybe some edible gold dust if you are feeling extra exuberant.
MORE ABOUT THE INGREDIENTS
AQUAFABA – that’s right, here I go again with my favourite bean juice (I love working with it as may you know by now). I used canned aquafaba from a can (two cans actually) of Morrisons’ organic chickpeas. There is no special reason why I chose this brand (my favourite is Biona but I cannot get it locally), I simply live fairly close to Morrisons so that’s the best option I had at my disposal. I typically use aquafaba from homecooked chickpeas, but I didn’t have the time to cook them. Make sure all your utensils, bowl and hands are spotlessly clean as aquafaba and grease hate each other like cats and dogs (that actually is not true as exemplified by numerous ‘my cat and my dog are BBFs’ videos but you know what I mean 😉 ). To banish grease, use a glass or metal bowl and wash your whisk attachments in soapy hot water carefully.
DARK CHOCOLATE – Both layers of this chocolate themed cake rely on quality dark chocolate. I used 72% dark chocolate and I recommend something similar, 70-74% is fine, any less and the mousse may not set as firmly as you would like.
COCOA – A good brownie benefits from some cocoa powder alongside melted chocolate. I used natural cocoa powder and I would recommend steering clear of Dutch-processed as it does not react with baking soda, which is used in this recipe.
SUGAR – I used two different types of sugar in this dessert, but you can get away with one too. For the brownie base, I used a combination of caster (superfine) sugar and dark muscovado, the first gives baked goods their signature crispy shell and the latter adds depth of flavour and add to the fudginess of the brownie. The mousse part needs caster sugar, also known as superfine sugar, as it dissolves easily in the mousse and does not cause any grittiness. I used it to help the mousse with its texture and also to sweeten it a touch.
VEGAN BUTTER – I used vegan butter both in the base and in the mousse. The reason for using butter (vegan in this case) in brownies is pretty obvious, but you may be wondering why I would add it to the mousse too. I added it to make the mousse firmer, firm enough to cut. It also stops the chocolate from seizing as it is melted alongside the chocolate, in the same bowl. What you need here is vegan butter that comes in a block (often called vegan block, in fact). I used Violife brand. You could substitute with coconut oil, I always recommend using odourless one to keep the flavour profile coconut-free.
FLOUR – I used plain flour to make the brownie base, but you can also make this cake gluten-free if needed. To do that simply use a well balanced gluten-free flour mix and a smidge (quarter of a teaspoon) of xanthan gum to help with binding.
BAKING SODA – A smidge of baking soda is needed to give these brownies a gentle lift. It comes into a chemical reaction with acidic cocoa powder and melted chocolate, which helps to lighten the batter a touch.
Whisk aquafaba in a spotlessly clean bowl until foamy, then add sugar until the mixture turns pale (white if only using caster sugar) and lots of little bubbles form – see picture on the left. Gently fold in melted chocolate and butter mixture.
Fold in all of the dry ingredients until the mixture is uniform and no lighter streaks remain. Transfer to the prepared baking tin, bake and cool down completely.
Whip aquafaba until stiff (it does not move when the bowl is inverted), gradually add sugar and melted chocolate mixture. Fold slowly and gently until no streaks remain. Top cold brownie base with the mousse mixture and refrigerate until set – at least overnight.
- 60 g / ¼ cup aquafaba*
- 125 g / ½ cup + 2 tbsp sugar (I used 50 % caster sugar, 50 % dark muscovado)
- 50 g / 1.75 oz vegan butter
- 75 g / 2.6 oz dark chocolate 70-74% cacao
- 25 g / 2 tbsp cocoa powder (not Dutch processed)
- 65 g / ½ cup plain flour (or GF flour mix + ¼ tsp xanthan gum)
- ¼ tsp fine salt
- ¼ tsp baking soda
CHOCOLATE MOUSSE LAYER
- 200 g / 7 oz dark chocolate 70-74% cacao, broken up
- 50 g / 1.75 oz vegan butter (I used Violife), cubed
- 240 g / 1 cup aquafaba (I used canned but homemade works too)
- ¼ tsp cream of tartar OR ½ tsp lemon juice
- 50 g / ¼ cup caster sugar
METHOD
BROWNIE LAYER
- Preheat the oven to 180° C / 355° F (160° C / 320° F with a fan setting). Grease the sides of a 20 cm / 8 inch baking tin and line the bottom – I used an adjustable baking frame on a sturdy baking tray.
- Place broken up chocolate and chopped vegan butter in a metal or glass bowl suspended over a water bath. Make sure the bowl does not touch the water underneath and use low heat. Once the water under the bowl starts to simmer, switch off the heat and allow the contents of the bowl to melt gently into each other in the residual heat. GENTLY and slowly mix them together.
- Whip aquafaba with an electric whisk until you get a dense foam, full of little bubbles (there is no need to achieve stiff peaks for this recipe).
- Gradually add sugar to the aquafaba, whisking well after each addition.
- Slowly pour very warm (otherwise the batter will become too stiff to add all of the flour) chocolate and vegan butter mixture into the aquafaba mixture and gently fold in until uniform.
- Mix flour, salt, cocoa and baking soda in a small bowl. Fold them in two batches, until no dry pockets remain.
- Transfer brownie batter into the prepared baking tin, spread it into the corners with a spatula. Bake for 17-18 minutes, allow to go cold before topping with the mousse.
CHOCOLATE MOUSSE LAYER
- Once the base is cold, gently remove it from the tin. Line the sides the the tin with baking paper and put the brownie base back in.
- Place chocolate and vegan butter in a metal or glass bowl suspended over a water bath. Make sure the bowl does not touch the water underneath and use low heat. Go to the next step while you wait.
- Place aquafaba and cream of tartar in a spotlessly clean bowl.
- Whisk on medium/high speed until you reach stiff peaks (when you invert the bowl, whipped aquafaba should stay put). Depending on your equipment, it may take around 8-10 minutes (it does for me and I have an old handheld whisk).
- Add sugar in 1 tbsp increments while whipping and slowly counting to 20 after each addition.
- Once the chocolate and butter have melted, stir them GENTLY into each other.
- Add a large spoonful of whipped aquafaba to the melted chocolate and fold it in very gently.
- Now, add about a third of melted chocolate into the whipped aquafaba and fold gently using a flexible spatula, when it’s roughly incorporated add another third and then the last third.
- When you’ve added all of the chocolate, carry on folding gently until no white streaks remain. Be gentle and slow or else you’ll knock too much air out of the aquafaba.
- Top cold brownie with the mousse and place in the fridge until set – at least overnight. Decorate* with cocoa powder and cut with a sharp knife.
NOTES
*DECORATION: While I decorated my cake with a cloud of Italian meringue, I would not recommend doing the same as this caused problems, which I did not realise until I came to cut the cake. The moisture in the meringue and the act of torching it with a chef’s torch weakened the mousse and made it impossible for me to cut a neat slice… Instead, I suggest a thin sprinkling of cocoa powder on top – as is traditional for a tiramisu – and maybe some edible gold dust if you are feeling extra exuberant.
