OK - here is what I did:

pureed apples - as usual
creamed 90g butter (without sugar - perhaps next time, might add sugar - they are a bit tasteless!)
add 1 egg
make into dough with one cup SR flour and one cup flour. I think I would possibly reduce SR flour next time, they're a bit fat.
added 2 tbspn milk to get a better consistency of dough.
rolled out as thin as possible into a rectangle
piped on apple puree in a line, rolled up dough once around puree, cut, and then chop into bars. Repeated with length of dough.
brushed with milk and baked at 160 for about 15 minutes.

They came out a little tasteless to me, but DS still really liked them and the puree was nice and intact. Texture was reasonably good. Not bad for a first go - will be happy to hear of improvements.