I made this back in June, and said it would become a regular here. Well, it hasn't, not because we didn't love it, but because we like trying new things too much to have many regulars!
Anyway, I saw it mentioned again recxently so tried a different recipe for it, from Serious Eats last night.
I think this was possibly even better than the first one.
I used sriracha again, as I couldn't get harissa yesterday, and I used my kewpie mayo in the white sauce. I'm getting addicted to this stuff, need to buy more!