Must cookies contain chocolate in BrE?

Solution 1:

Until recently, cookie was a foreign word in British English: because of American TV and films, most people knew that it was American for biscuit.

Cookie is now familiar for the large, sweet, not-very-crunchy confections sold in shopping malls. They come in various flavours, and don't have to have chocolate.

I don't think anybody I know would call traditional-style English biscuits (whether Bath Oliver, Malted Milk, Garibaldi, Ginger nut, Fig roll, or even Hobnob) "cookies".

Solution 2:

Firstly, in British English, a cookie is a biscuit, just a specific kind.

As a British English speaker, I would say cookies don't have to include chocolate, although they usually do. I would go further and say that cookies have a very specific meaning here - they are round, flat and contain chips (typically chocolate). If there are no chips, but are covered in chocolate then they are simply a chocolate biscuit.

So, these are cookies, irrespective of whether they are crisp or chewy:

I did try to find an image of cookies without chocolate chips (e.g just nuts), but they invariably do contain chocolate, although sometimes white. Nevertheless I believe a macadamia chip cookie just about qualifies

Whereas, these are chocolate biscuits.

And this is an ordinary biscuit

And this non-cookie status for chocolate biscuits also extends to sandwich style biscuits, so this is not a cookie either:

And incidentally the above image is far inferior to this UK delight