Adapted from Leith’s Baking Bible
140g dark chocolate, chopped into small pieces
115g unsalted butter
225g caster sugar
170g plain flour
1/2tsp baking powder
200g chestnut purée
3 eggs, beaten
1 Heat the oven to gas mark 3, and line a 20cm square cake tin with baking parchment.
2 Melt the chocolate, butter and sugar in a heavy bottomed saucepan over a low heat. Don’t let it get too hot.
3 Sift the flour and baking powder together into a large bowl.
4 Mix the chestnut purée into the chocolate mixture.
5 Make a well in the flour and incorporate the eggs and chocolate mixture. Use a whisk if you need to, to break up any lumps of flour.
6 Put the mixture into the cake tin and spread it flat. Bake for 20 minutes, and allow to cool completely in the tin before cutting into squares.
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