I must share this cake with you. I have been making it a lot in recent weeks. Mostly because it keeps getting eaten before I have had chance to take a photo of it. Each time I fetch it out of the oven I say ‘now, I must get a photo of this cake this time’, then it’s gone. But I have also been making it because (and this is a really good excuse) chestnut flour doesn’t keep well, so you must use it quickly.
I buy my bread flour by the 25kg sack full from Shipton Mill. To get free delivery I always add to the order and this time I included chestnut flour. It’s not cheap but I have wanted to try it for ages. I am glad I did. It is seasonal so you may have to wait to make this cake.
This cake is fudgy and dense, like a brownie in texture. I have tried all caster sugar, all light brown sugar and half and half caster with muscovado. My favourite is to use all light brown sugar. It gives a caramel edge without being too heavy or bitter. The cake is even better the day after it is made as it just gets fudgier. Be careful not to overcook it though. You want a slight wobble left in the centre when you take it out of the oven. This will firm up when the cake is cooled and your cake will be lovely and moist.
If you have chestnuts rather than chestnut flour then I can recommend my other Chocolate Chestnut Cake as being equally delicious.
200g dark chocolate (at least 70% cocoa solids and stuff that you enjoy eating)
200g unsalted butter
200g soft light brown sugar
4 eggs, separated
100g chestnut flour
Preheat the oven to 170°c, gas mark 3 or use towards the bottom of the baking oven of the Aga. Grease and line a 20cm cake tin with baking parchment.
Break the chocolate into small pieces into a bowl. Cube the butter and add to the chocolate. Melt the butter and chocolate in the bowl over a pan of gently simmering water (making sure the water does not touch the base of the bowl). When melted stir gently to combine.
Whisk the egg yolks and the sugar together until well combined and slightly paler in colour.
Whisk the egg whites in a separate, scrupulously clean bowl to firm peaks.
Add the melted chocolate and butter mixture to the egg yolks and sugar mixture and combine well. Fold in the chestnut flour. Add one third of the egg whites, mixing in well so that the mixture is light and the remainder of the eggs can be very gently folded in, retaining as many of the tiny bubbles as possible. When all combined, gently pour the mixture into the lined tin and place in the preheated oven and bake for 20-25 minutes. It may take a few minutes longer depending on your oven but check at 20 minutes as you don’t want to overcook it.
Leave to cool in the tin for about 20 minutes and then turn out onto a plate. You can dive in straight away or restrain yourself and keep until the next day.