Chocolate Ganache Topping for Jaffa Cake Tart

Our answer

Chocolate ganache is a mixture of melted chocolate and double (heavy or whipping) cream which is popular both in confectionery, as a truffle centre, and also in cake making, as a frosting or filling. One of the advantages of using a ganache is that it tends to hide the slightly dull finish that you get from melting chocolate and leaving it to set. To get a very shiny finish to pure melted chocolate and a characteristic "snap" you need to go through a procedure called tempering, which involves heating and cooling the melted chocolate to specific temperatures. A ganache will not give you a high gloss finsih either, but it looks a little better than straight melted chocolate and will not set quite as quickly as melted chocolate, making it slightly easier to spread over a cold surface.

The softness of the ganache will depend upon the ratios of chocolate and cream. Using twice the weight of chocolate to cream (eg 200g/7 ounces chocolate to 100g/100ml/3 1/2 fluid oz/7 tablespoons cream) gives a ganache which will set fairly firmly at room temperature and equal quantities of chocolate and cream will give a much softer, truffle like mixture (and also a fabulous sauce for ice cream when warmed up!). We would suggest you reduce the quantity of cream in the topping to make the ganache firmer. Without seeing the exact recipe it is difficult to be specific about quantities but we would suggest that it is easier to reduce the cream by quite a bit as you can always warm the ganache and stir in a little extra cream if the ganache isn't spreading well. Also try to spread the ganache over the jelly filling when it is not fridge cold as it will also make the ganache easier to spread (this will probably involve letting the jelly set then taking the flan out of the fridge for a while to take the chill off).