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 Thermomix on 50 degrees, 3 minutes, Speed 2. Set aside to cool.
Wash and dry the Thermomix bowl. Insert the butterfly and add the caster sugar and eggs. Beat on Speed 4, 6 minutes.
Reduce to Speed 3 and with the butterfly still turning, slowly add the cooled chocolate mixture, ground almonds, plain flour and salt. Mix on Speed 3 until combined (you might need to scrape down the sides of the bowl partway through).
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.