Heston's Two-ingredient chocolate mousse

“Sometimes rules are made to be broken. Water is supposed to be the enemy of chocolate but here it’s the key to a mousse that’s astonishingly simple to make and, since no cream is involved, has a gratifyingly intense chocolatey flavour.”

Ingredients

350g dark chocolate, 70% minimum cocoa solids, finely chopped 
270ml hot water

Method

1 Place the chocolate in a bowl and add 270ml of hot water. Using a whisk, mix until the chocolate has dissolved.

2 Place the bowl over an iced water bath and whisk until the mixture begins to thicken.

3 Remove the bowl from the iced water bath and continue whisking until the mixture just becoming soft set. Serve immediately.