I get confused when a recipe asks for chocolate in baking. For example 200g of dark chocolate when making a cake, do I use cooking chocolate or eating chocolate? Jenni
If a recipe askes for dark chocolate we tend to recommend using a dark chocolate with 70% cocoa solids (cocoa mass and cocoa butter). This would be most commonly regarded as an "eating" chocolate though sometimes it will be sold in both the confectonary and baking sections of the supermarket. The high level of cocoa soids gives a deeper chocolate flavour which is useful in baking. For milk and white chocolates we would suggest using a good quality "eating" brand of chocolate.
In the UK there is a type cooking chocolate used for cake covering (often known as Scotbloc). This is formulated so that it melts quickly and retains a glossy finish after melting (regular chocolate needs tempering to remain glossy after melting). It is good for cake decorating and can be used for cooking, but we prefer to use other chocolates for cooking.
In the US we prefer to use bittersweet chocolate which usually has 62% cocoa solids as it is the closest US chocolate to the 70% type found in the UK. Some good quality UK and Europen brands of 70% chocolate are also available in the US. Unsweetened baking chocolate has no added sugar so is a little too bitter for Nigella's recipes which are tested using eating types of chocolate.