Preheat oven to 160 degrees celsius (fan-forced). Grease and line the base and sides of a 23cm springform tin with baking paper.
Melt the butter and chocolate together in the microwave on 50% power for 2-3 minutes (stirring every 30 seconds until melted). Set aside to cool.
Beat the caster sugar and eggs together until pale, creamy and slightly thickened (this will take approximately 5-8 minutes).
Gently fold through the cooled chocolate mixture, ground almonds, plain flour and salt using a large metal spoon.
Bake for 30 minutes or until set in the middle (the top will form a lovely crust).
Allow to cool in the tin for 15 minutes before removing to a serving plate. Serve dusted with cocoa powder, fresh raspberries and ice-cream.