Preheat oven to 160C/140C fan forced. Release base of a 22cm springform pan, invert, line with baking paper, and grease the side with melted butter.

Melt chocolate, butter, sugar, and water in a heatproof bowl over simmering water. Remove from heat and stir in flours, cocoa, and egg. Pour the mixture into the pan and bake for 25 minutes or until a skewer comes out clean.

Cool the cake completely in the pan.

For the mousse, place chocolates in a heatproof bowl over simmering water and stir for 3-4 minutes or until melted and smooth.

Remove from heat and set aside to cool slightly. Use electric beaters to beat cream in a bowl until soft peaks form. Fold a third of the cream into the chocolate mixture, and repeat twice until well combined.

Spoon mousse into the pan, tap on the bench to remove air pockets, and smooth the surface with a spatula. Place in the fridge for 6 hours or overnight to chill and set.

For the glaze, combine chocolate, cream, and glucose in a small saucepan. Stir over low heat until melted and smooth.

Cool slightly and pour over the mousse. Place in the fridge for 1 hour to set. Serve cut into wedges.