Prepare an ice bath by placing a tray of ice cubes with water to cover them in a large mixing bowl. Place a smaller bowl inside.

Weigh 40g (1.5oz) water into a small saucepan. Break chocolate into chunks and add to the water.

Place over a low heat and stir for a minute or so until the chocolate is just melted… Be careful not to let it get too hot or the chocolate will split.

Transfer melted chocolate to the smaller bowl and whisk until you have a light moussy texture. Transfer to pretty serving glasses.