Picture posting is enabled for all :)
Perhaps someone knows of good ways to serve them, roast sounds one good method ...
Ooh, now you're asking! too shallow would be, erm, 4 inches deep and upwards. Best depth 4-8 inches, heavy to light soil.
But if you think you have planted too shallow you could earth them up like spuds :)
The easiest thing to do with these is to leave them on the same bit of ground permanently, as they don't seem to suffer from disease, and getting all the tubers out is hard going.