Sometimes only a square of shortbread will do. When I need comfort or a little afternoon pick me up, it’s hard to resist the call of a buttery, crumbly piece of shortbread – even more so if I can find some with dark chocolate chips in it.  Good ol’ Marks and Spencer is my usual failsafe haunt in times of need, but finding myself stuck at home during the lockdown, meant I needed to find a different way to get my fix. I first started making shortbread while working at Pendennis Castle Coffee Shop back in my student days. It…