Hi, can I subsituite a little of the plain flour for some cocoa when making biscuits to make them chocolate biscuits? Vickie.
It is possible to switch some plain (all-purpose) four for cocoa in cookie recipes but the texture may change slightly. This is partly as cocoa doesn't contain any gluten so a cut-out cookie dough may be slightly more difficult to roll out, but the finished cookie will be more tender and crumbly. The downside is that cocoa absorbs more liquid than flour so the cookies can be a little dry.
We would suggest not switching more than 25% of the flour for cocoa and initially using a straight substitution of cocoa for flour. If the cookies are too dry then reduce the amount of cocoa slightly. Also add a pinch of salt to the flour when you are making the cookies as salt tends to help to bring put the flavour of the cocoa. Finally, you can add some cocoa and vanilla to a glace icing to ice the cookies with, or try the chocolate cookie icing on p206 of Christmas.