This time, I used a bag of chilli-flavoured peanuts. Chopped a small handful, ground the rest down to a powder in the blender, then mixed in the oil in a separate bowl. Much easier this time. And it’s a good result – a pleasant orangey colour, with normal peanut butter tastiness followed up by as much chilli heat as you’d probably want in a sandwich.
Might not work so well in a peanut butter and jam sandwich, mind. Cream cheese, maybe, but jam, no.