Do the onions have to be left whole while roasting? or can the ends be cut off

Hi Panfusine,
This is Amy from ChefSteps.com. We recommend you leave them whole. It helps them steam while roasting and keeps them from becoming too dry. Hope this helps.

Panfusine, I've roasted them both with roots intact and cut off. The ends, as far as I can see, give no taste difference. Merely convenience when serving them as part of a vegetable platter, so diners can have a unit to pick up. For this recipe, since all will be puréed anyway, might as well cut the ends off before you roast.