It was dead easy to make, and due to the partner's request for plain shortbread I put about a fifth of the plain mixture in the tin before folding the chocolate chips into the rest of the mixture.
I was really pleased with the results - it is indeed rich and buttery, and had a great texture. The 3-year-old was very excited throughout the baking process, and attacked the first piece I gave him with enthusiasm. By the second piece, however, I noticed that he was just picking out the chocolate chips, and thereafter he asked for chocolate chips on their own, which was a little disappointing. The partner loved the plain version and has requested I make it again soon.
It just so happened that we were going to a picnic the next day, so I duly packed a box of the chocolate chip version (as was under strict instructions to leave all the plain at home for the partner to eat during the week) and it was a big hit - with children and adults alike. In fact I had to hide the box from one 3-year-old after I saw him reaching for a fourth piece...
Verdit - I would definitely make this again, although I might try with dark chocolate chips next time.