Serves: 4Preheat the oven to 180°C/gas mark 4.
Grease the inside of a 20cm springform tin and line the base with a disc of buttered baking parchment.
Dust with 1 tablespoon cocoa and tip out the excess.
Tip 200g pre-cooked, peeled chestnuts into a small frying pan, add 2 tablespoons caster sugar and 100ml full fut organic milk and cook over a low-medium heat for 5 minutes until the chestnuts start to soften.
Remove from the heat and tip into the bowl of a food-processor and whizz until smooth.
Add 1 teaspoon vanilla extract and cool.
Place 100g unsalted butter and 150g chopped dark chocolate in a heatproof bowl and melt either in the microwave on a low setting or over a pan of barely simmering water. Stir until smooth, remove from the heat and cool slightly.
Whisk 3 large organic eggs and 75g caster sugar until thick, pale and doubled in volume.
Mix in the chestnuts until thoroughly combined. Add the melted chocolate mixture and fold in until smooth.
Carefully pour the batter into the prepared tin, spread level and bake on the middle shelf of the preheated oven for about 30 minutes until risen and the top has formed a light crust.
Remove the cake from the oven and set the tin on a wire cooling rack and leave to cool to room temperature.
The cake will sink and the crust might crack as it cools but this is part of the cake’s appeal. Dust with cocoa and serve with crème fraîche.