such as here. The Waitrose recipe goes for the anchovy butter simply spread on toast, rather than made into little toasted sandwiches, but apart from that it's identical.
This recipe was surprisingly easy to make, although it took way longer to cook than the 15 minutes stated. More like 45 minutes I'd say. I have to say that after the waiting around and tentative bain marie shaking, I was a little disappointed that the Parmesan custard wasn't a bit more cheesy. However on reflection, the contrast between the salty, fishy toast and the creamy custard, was very acceptable and more Parmesan would probably have been overwhelming (I am still tempted to make it again with more cheese though). Anyway, I really liked this recipe and particularly the toast part and will definitely be cooking it again in the near future (possibly with extra cheese).