I remembered that I'd bought some once before, but didn't recall whether we liked them or they were disappointing. I WhatsApped my wife, and she had the same feeling: either we loved them or they were so-so. She suggested I went for it, so I did.
This being an airport duty-free shop, they were expensive — €16.25 — so I was hoping that at least one of us would like them. On the flight home, I was relieved to dredge up a memory that indicated we did indeed like them, and this proved to be true when we got home.
They're great! I don't know what they're made of (some kind of very soft nougat?) but they're amazingingly good if you like pistachio, better than the recent Dubai chocolate fad in my opinion. €16.25 for a single slab is pricey, though, and as the top two pistachio-producing countries in the world, the United States and Iran, are currently at war, I don't expect them to get any cheaper.
Still, at least it makes it easy for me to decide what present to buy my wife next time I find myself in Spain on a solo trip.