ganache

Ganache (pronounced /ɡəˈnɑːʃ/, from the French word for "jowl") refers to a variety of icing, fillings for pastries, and glazes. It is typically made from chocolate and cream. Its origins date to around 1850, when it may have been invented in Switzerland or in France.

Ganache is normally made by heating heavy/double cream, then pouring it over chopped dark chocolate. The mixture is stirred or blended until smooth, and can be enhanced with liqueurs (e.g. coffee, cocoa, cherry, etc) or extracts (e.g. vanilla, almond, chestnut, hazelnut, etc). Depending on the kind of chocolate used, what the ganache is intended for, and the temperature it will be served at, the ratio of chocolate to cream can vary to reach the desired consistency.

Ganache can also be used in filled chocolates, chocolate truffles, and other desserts. The portions of chocolate to cream vary depending on the intended usage of the ganache. Typically, a ganache is chocolate and cream in a 2:1 ratio; this is used for filling cakes or a chocolate truffle base. For making a glaze, three times as much chocolate as cream is commonly used. Ganache can also be allowed to cool and whipped to increased volume and then spread to cover a cake.

(Source: Wikipedia)