Heat oven to 160C/140C fan/gas 3.
Butter and line the base and sides
of a deep 22cm cake tin with baking
parchment, then beat the rest of the
butter and the sugar together until pale.
Add the flour, baking powder, vanilla,
eggs, yogurt and grated chocolate.
Beat together, then stir in the peaches.
Scrape into the tin and bake for 1 hr,
until an inserted skewer comes out
clean. Cool in the tin.
To make the icing, melt the chocolate
chunks in a bowl over a pan of barely
simmering water, then remove from
the heat. Beat the soft cheese in a
mixing bowl until smooth, then beat in
the yogurt until smooth. Scrape in the
melted chocolate and beat again. Chill
until ready to use.
Swirl the icing over the top of the
cake and scatter over the pistachios.