I forgot to take pictures, but they were well liked at the party and all eaten over the rest of the weekend. I think they may have benefited from a light sprinkling of finishing salt on the top. But I didn't think of that until I was at the party.
These bars actually traveled quite well and lasted out of the refrigerator for a couple of hours before serving. They may be even more delicious chilled but I didn't feel the need to cram them in the hostess' fridge.
This is the measurements I used, adapted from Epicurious:
For shortbread crust:
For chocolate dulce de leche: