Step 1
Add the chocolate and butter to a medium heat-proof bowl. Microwave in 30 second bursts, until chocolate and butter has completely melted. Set aside to cool for 5 minutes, then stir through the icing sugar, egg yolks, ground almonds, flour and salt. Add the egg whites to a large bowl. Using electric hand-held beaters, beat the egg whites on high speed for 1-2 minutes, until medium-stiff peaks. Gently fold the egg whites through the chocolate mixture, until just combined and no streaks remain. Pour the mixture into the prepared cake tin. Bake on the lower-middle oven rack for 18-20 minutes until risen but still jiggly in the center (you want it to be gooey & molten, not set). Set aside to cool in the tin.