Swiss walnut and chocolate cake

Method

1. Preheat the oven to 180°C/fan 160°C/gas 4. Grease and line a 22cm diameter cake tin with baking paper.
2. Melt the chocolate in a heatproof bowl set over a saucepan of barely simmering water, making sure the surface of the water does not touch the bowl. Leave to cool a little.
3. In a large bowl, cream the butter and sugar together until pale and fluffy. Beat in the eggs, one at a time, then sift in the flour and baking powder and carefully fold in. Add the melted chocolate and the vanilla, then fold in the chopped walnuts.
4. Spoon into the prepared tin, then arrange the walnut halves on top in a circular pattern. Bake for 30-35 minutes until a skewer pushed into the centre comes out without any raw batter sticking to it (the texture will be similar to a brownie).
5. Leave to cool in the tin for 10 minutes, then transfer to a cooling rack to cool completely. Dust with icing sugar and cocoa powder.