Where can I buy natural unsweetened cocoa powder in the UK, for recipes like Nigella's Devil's Food Cake? Is cacao powder the same thing?
In the UK there is no particular differentation between natural cocoa powder and Dutch processed cocoa powder (both are unsweetened) and for Nigella's Devil's Food Cake (from KITCHEN) both types of cocoa powder will work. Cocoa powder is made from dried, roasted and ground cocoa beans and natural cocoa powder has nothing added and some will describe the taste as fruity and slightly acidic. Dutch processed cocoa powder is treated with an alkaline and has a darker colour and a more mellow flavour. Natural cocoa powder is slightly acidic so can work slightly better in baking recipes that use just bicarbonate of soda (baking soda) as the leavening agent.
In the US cocoa powder is labelled as natural or Dutch processed. In the UK it is possible to buy both types, but you will need to look at the ingredients label to see if it is Dutch processed. The Dutch processed version will have "acidity regulator" listed in the ingredients. At time of writing the Green & Black's cocoa powder is Dutch processed and Cadbury's is a natural cocoa powder. Cacao powder is made from unroasted cocoa beans and can be used as a substitute for cocoa powder and is closest in flavour to natural cocoa powder.