Ganache comes from an old French word meaning pillow. And effectively that's what a ganache is, a little pillow of delicately blended chocolate and cream. The mixture is traditionally made by blending chocolate, cream and sometimes butter together. But modern chocolatiers have taken to making in with different ingredients and methods as we'll discover. Depending on how it is made it can be used to fill chocolates, cakes, macarons, to make truffles and as a glaze for cakes and dessert recipes.
The age old method for making a ganache is to heat cream until it is just at boiling point then pour it over chopped chocolate or callets (chocolate buttons used by professional chefs & chocolatiers). The cream is left to sit on top of the chocolate for 30 seconds or so, before the chef slowly stirs from the centre incorporating the cream with the melted chocolate. What is happening here is that the cream and chocolate are forming an emulsion. Some chefs prefer to incorporate cream at around 45c to already melted chocolate at the same temperature. In any event the aim is to achieve a fully emulsified, silky smooth result. This can be helped by using a hand blender immersed into the liquid mix- Note it must be kept below the surface, as air should not be introduced into the ganache mixture. Once fully blended butter may be added to increase the richness, but also the firmness of the final ganache.
If using for truffles, ganache is ideally left at room temperature for 4hrs before refrigerating until the desired working texture is achieved.
Ratio wise, for truffles and fillings a 2 parts chocolate to 1 part cream formula is generally used. For coating cakes the cream element may be increased slightly and sometimes sugar syrup is blended in for glossier results. Other variations will include the addition of fruit purée, flavoured oils, nut pastes, alcohol, or infusing herbs and spices into the cream from the outset.
The traditional method outlined above is used by most people. However for those seeking even greater flavour heights there lies one problem with the traditional method of making ganache and that is that cream and butter mask flavours. Just think about how you dull down the spices in a curry if it's too hot - by adding cream or yoghurt. The same things happens when you add it to chocolate, it dulls all those beautiful top and bottom notes that make up a great chocolate, along with whatever flavours you have chosen to add. So some chocolatiers and chefs have started to make ganaches without the use of cream, using what many refer to as the water ganache method, where water, a flavoured liquid or fruit purée is used instead of cream. This presents a number of problems, but when solved properly can deliver exceptional length, depth and clarity of flavour.