Use any biscuits you like. I used Tim Tams that great Australian treat because they are milk chocolate and they go well with the dark chocolate used in the rest of the cake, but you can use any biscuits you like including gluten free ones. The new Adriano Zumbo flavoured Tim Tams would be good. This recipe uses Australian cups
I used 150gm "Tim Tams" ( 6oz) and 100gm (3.5oz) plain biscuits)
Make sure your chocolate doesn't conytain barley for those that are gluten free. Lindt chocolate commonly contains barley