I made these tonight with some leftover condensed milk. Absolutely delicious. As you say Chookie, unusual, but very flavoursome, quite rich I thought - a small piece is plenty - but really yummy (and terribly easy!).
Thanks for posting the recipe.
Oh, I did make a couple of changes due to items missing from my pantry. I used almonds instead of walnuts (which I thought added a really pleasing texture and crunch) and I didn't quite have enough butter so I had to use 25g of oil. Didn't seem to have any adverse impact.