Preheat the oven to 180C/Gas Mark 4. Grease a 23cm springform tin and line with baking paper. Bring the water to a boil in a saucepan. Turn the heat down to low and add the chocolate chunks and coffee, stir continuously until all the chocolate is melted.

Add the butter and stir until all combined, whisk the egg yolks with the sugar until fluffy and doubled in size, in a separate bowl, whisk the egg whites until stiff peaks form.

Now fold the melted chocolate mix into the egg yolk mix, carefully fold 1/3 of the egg whites into the mix. Now fold the rest of the egg whites in, being careful not to overwork it.

Pour the mix into the prepared tin, then bake for 50 minutes or until a skewer comes out clean. Leave to cool on a rack before transferring into the fridge for a few hours. Serve with your preferred topping or on its own.