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

Melt chocolate, butter, sugar, and water in a heatproof bowl over simmering water. Remove from heat. Stir in flours, cocoa, and egg; pour into pan. Bake for 25 minutes or until a skewer comes out clean.

Cool cake completely in pan.

For mousse, place chocolates in a heatproof bowl over simmering water (don't let the water touch the bowl). Stir for 3-4 minutes or until melted and smooth.

Remove from heat and set aside to cool slightly. Beat cream in a bowl until soft peaks form. Fold a third of the cream into the chocolate mixture. 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 saucepan. Stir over low heat until melted and smooth. Cool slightly and pour over mousse. Place in the fridge for 1 hour to set.

Serve cut into wedges.