Cut them into even sized pieces works best I find. Blanche them in boiling water and shake dry.
I put them into the ashet ( think deep pie dish sort of shape tin) and shake them about a bit with salt, pepper, a wee bit of ground rosemary if you like it, and a drizzle of good oil. A friend says they're brilliant with some bacon fat instead of the oll though.
You can speed the roasting up by nuking them in the microwave for three or four minutes first.
It helps keep them from drying out too much, just do them hot in the oven thereafter.
Have a prod at them with a sharp knife every so often, make sure the cores are cooked.