Preheat oven to 180 degrees C. Line bottom and sides of a 22cm springform pan with foil.
Melt butter and chocolate over a low heat. Stir until smooth then let cool.
In a mixing bowl whisk egg whites until stiff; about 2 minutes. In a separate bowl whisk together yolks and sugar until thick and pale; about 1 minute.
Blend in chocolate mixture with the almonds then fold in the whisked whites a third at a time into chocolate until completely combined. Move to the prepared springform pan.
Place a 20cm baking dish with 3cm of water in it on the bottom rack of the oven.
Bake torte on centre rack at 180 degrees C for 45 to 50 minutes or until sides begin to pull away from the pan and top is set in the centre. Cover the torte loosely with foil for the last 20 minutes of baking.
Cool on wire rack for 10 minutes and then carefully remove the sides of springform pan. Invert onto a serving plate and cool completely.