Grease the tin with butter and coat with 10g of ground almonds.
Melt 150g of chocolate over simmering water and let cool for 15 minutes.
Preheat the oven to 190°C.
Cream 150g of butter and icing sugar until light.
Beat in egg yolks followed by chocolate, 50g almonds, flour, and baking powder.
Whisk egg whites to stiff peaks and fold into the chocolate mixture.
Bake in the centre of the oven for 35 to 40 minutes.
Cool for 3 minutes in the tin before turning out onto a wire rack.
Melt the icing ingredients over simmering water and stir until smooth.
Drizzle the icing over the cake and decorate with flaked almonds.
Wait one hour for the icing to set before serving.