Method

• 1.
  Place prunes and liqueur in a bowl and set aside for at least 15 minutes. Preheat oven to 150°C/130°C fan-forced. Grease base and sides of a 22cm springform pan and line with baking paper, extending paper 2cm above pan.
• 2.
  Place chocolate and butter in a large heatproof bowl over a saucepan of simmering water and stir until smooth (make sure bowl doesn’t touch water). Remove from the heat.
• 3.
  Whiz walnuts in a food processor until a crumb texture. Whisk egg yolks and brown sugar in a large bowl until pale, thick and doubled in volume. Add chocolate mixture and whisk until combined. Add walnut crumb and any remaining liqueur that the prunes haven’t absorbed and stir until combined.
• 4.
  In the bowl of a stand mixer fitted with the whisk attachment, whisk egg whites and caster sugar until soft peaks form. Add one-third to the chocolate mixture and whisk until combined. Gently fold through remaining egg white mixture in two batches (do not overmix). Spoon three-quarters into prepared pan. Arrange prunes on top. Cover with remaining batter. Bake for 50-55 minutes until top is set and a skewer inserted in the centre comes out with moist crumbs attached. Cool completely in pan. Serve dusted with cocoa, with whipped cream alongside.