The bottom line is that you can use foil for many of the same things you would use parchment paper for, but it doesn’t mean you always should. If parchment paper is for hot use, and waxed paper is for cold use, think of foil more as your alternative for insulating use.
Keeping this in view, do you need parchment paper to roast vegetables?
In our guide to roasting any vegetable, we recommend parchment paper—no questions asked (or explanation given). … In Bon Appétit’s Ultimate Guide to Roasting Your Vegetables, they don’t recommend lining the pan for broccoli, brussels sprouts, squash, carrots, cauliflower, or sweet potatoes.