So now we have a sort of burnt-sugar version of milk toffee (it does still taste good, thankfully), in what now smells like a modernist kitchen, as Kat says. I think she's figured out what the problem was -- my recipe called for two T of vanilla, which seemed like a lot, and I think, on comparison with other recipes online, that it's supposed to be two t. of vanilla. She thinks the extra alcohol might be what's throwing off the confectionary process. If I have the energy, I may make another, hopefully proper, batch in the morning. Science!