Chocolate chestnut chiffon cake (CCCC)

Again, another chiffon cake, but this time, I used the chiffon for a reason, not just because I love it! The main character of this cake is the chestnut, first it's in season and second it's also festive as we are approaching christmas! However, one thing to be aware of is that chestnut flavour can be quite subtle and you can't really combine it with heavy flavours as they WILL mask the chestnut completely and this is the reason I have chosen a plain vanilla chiffon. When done right, not only can you taste it, but you can also smell the sweet aroma of the chestnut too! 

Ingredients

• 115g self raising flour
• 1/2 tbsp baking powder
• 3 tsps pure vanilla essence 
• 170g caster sugar (put 90g, 30g and 50g into 3 separate bowls)
• 3 egg yolks
• 4 egg whites
• 80 ml cold water
• 90 ml vegetable oil
• 250g chestnut (sainsbury's whole chestnuts cooked and peeled works great)
• 400ml double cream
• 1 tbsp dark rum
• 50g milk chocolate
• 20g white chocolate
• 50g dark chocolate

1. Pre-heat oven to 170 degrees C and grease an 8 inch tin with unsalted butter
2. Sift and weigh flour, baking powder and 90g caster sugar and mix together
3. Add 2 tsps vanilla essence, egg yolks, water and vegetable oil to the flour and mix with metal spoon until a runny creamy mixture
4. Whisk with electric whisk egg whites  until soft peaks and gradually add sugar from 50g one tbsp at a time to egg white until it forms firm peaks and glossy
5. Gently fold in a third of meringue into the cake batter at a time until all the meringue has been folded in
6. Pour cake mix into baking tin and bake for 60-70 minutes. The surface should start to brown, but don't worry, it's supposed to. Turn the cake upside down immediately when it's out of the oven to prevent collapsing It is better that it is slightly brown as it will prevent the sponge to fall out of the cake tin when it's turned upside down
7. When the cake is completely cool (I usually just leave it upside down for 2 hours, start preparing chestnut cream at this stage), use a sharp knife and cut the edges of the cake to get it out of the cake tin
8. Cut the sponge horizontally with a sharp knife to divide the sponge in half for when the fillings are ready

Chestnut cream (creme aux marrons) 

1. Put chestnut and 200ml double cream and 20g caster sugar into a saucepan and heat over medium heat with occasional stir with wooden spoon
2. The cream should start to boil and thicken, add the rum and 1 tsp vanilla essence and let it simmer for a 2-3 minutes on low heat
3. Crush the chestnuts and mash them up slightly (it's almost like making potato mash)
4. Puree the chestnut cream with a electric blender, you can make it very smooth or leave some small lumps in (I actually prefer them with small lumps, but some people will prefer a smoother finish)
5. Whisk 100ml double cream until it thickens and spread a thin layer of cream across the inside of the sponges and put a very generous amount of chestnut cream on top of the double cream (I had about 5 mm high chestnut cream as the filling) and then put another layer of whisked double cream on top of chestnut cream
6. Put the other sponge on top 
7. Use remaining chestnut cream to cover the top and sides of the cake, smoothen it with a palate knife

Decorations

1. Make chocolate decorations by melting dark chocolate over a pan of simmering water and pipe it into any shape you want on a piece of parchment paper and let it cool in the fridge for at least 1 hour, you may even want to make tempered chocolate, but I haven't tried that yet myself
2. Make milk chocolate ganache by melting the milk chocolate (cut into small chunks) in 50ml of hot double cream and let it cool slightly, do NOT add any sugar
3. Pour over the top of cake to get a smooth finish 
4. Melt white chocolate over simmering water and pipe a swirl on the surface of the milk chocolate ganache
5. Use the tip of a blunt knife to run in and out of the white chocolate swirl to create a lovely flowery pattern
6. Lift the dark chocolate patterns off parchment paper and stick them onto the sides