Stove method:

1) Pour water into a saucepan and bring it to bowl over the stove. 2) Once the water is boiling, remove from fire and add in the cooking chocolate. 3) Return the saucepan to the stove and bring the mixture to a boil, stirring to melt the chocolate. At first the liquid will be very watery. 4) Simmer the chocolate for 5 mins, stirring often with a wooden spoon, until the water has mostly evaporated and the ganache is very much thickened. It will have a “pudding consistency”, as Rose Levy Beranbaum's Cake Bible explains this technique, “it will fall from the spoon and pool slightly before disappearing". Whisk until smooth before using.

Microwave method: 1) Microwave the chocolate and water together in a bowl for twenty-second bursts on high power until the chocolate is melted and the liquid resembles a cocoa drink. 2) Reduce the microwave heat to half and microwave in 30 second bursts, stirring at intervals, until the ganache is thick, almost like pudding, and falls from the spoon and pools slightly before disappearing. Whisk until smooth before using.