1.Preheat oven to 160°C (140°C fan forced). Grease a deep 25cm (10-inch) round cake pan, line base and side of pan with baking paper.
2.Place chocolate and butter into a small saucepan, stir over low heat until smooth. Remove from heat.
3.Blend sifted cocoa with the water in a large bowl, whisk until smooth. Whisk in melted chocolate mixture, sugar, almonds and egg yolks until combined.
4.Beat egg whites in a small bowl with an electric mixer until soft peaks form. Fold into chocolate mixture, in two batches. Pour mixture into pan. Bake about 1 hour, cool cake in pan.
5.Meanwhile, make toffee. Combine sugar and the water in a small saucepan, stir over high heat, without boiling, until sugar dissolves. Bring to the boil, boil, uncovered, without stirring, about 12 minutes or until light caramel in colour. Pour toffee onto tray, cool. Break toffee into pieces.
6.Turn cake top-side up onto a board. Dust cake with sifted extra cocoa. Cut cake into wedges with a hot dry knife.
7.Process toffee and mint leaves until finely chopped. Serve cake with scoops of ice-cream and mint toffee.
A closed 25cm (10-inch) springform pan can be used to make this cake. Once the toffee is processed with the mint leaves, it will become sticky and must be used immediately.Note