Preheat your oven to 180˚C (350˚F/160˚C Fan). Line and grease your cake pan, as required.
Break the chocolate up into little pieces and place in a bowl.
Add the butter to the bowl, and melt the chocolate and butter at 50% power in your microwave oven for 60 seconds. Stir, then another 60 seconds. Stir this until you have a smooth and shiny mix. Set aside.
Mix the almonds and cornflour.
Separate the eggs, placing the egg whites in a medium sized bowl and the egg yolks in a large bowl.
Beat the egg whites with 2 Tbsp of the sugar until stiff. Set aside.
With the same beaters, beat the egg yolks with the rest of the sugar until pale.
Add the chocolate mix and stir, using a wooden spoon or a rubber spatula, until you have a smooth mixture.
Add the ground almonds to the egg yolks, and fold it in, using the wooden spoon or a rubber spatula.
Finally, fold in the egg whites in 2 additions.
Pour into the prepared tin and bake for 35-40 minutes. Check at the 35 minute mark with a cake tester or long thin skewer. If it comes out clean, the cake is done.
Notes
Makes an 8" (20cm) cake. You will need to grease and line your cake pan, as required. The cake pan you see me using in the video doesn't need to be lined.