Whether I roast my vegetables on parchment paper or directly on the baking sheet has nothing to do with a recipe or a technique and everything to do with laziness. I make a quick calculation in my head: Which will take more effort—cleaning that oily baking sheet later, or bending down, opening the drawer, and then cutting a sheet of parchment paper now?
Since I'm all about living in the moment (or, um, minimizing only the most pressing pain-in-my-butt), I usually choose to roast sans lining (which, yes, means more de-greasing later on).
But, in terms of vegetables, does how I prep the pan make a difference?
It turns out—at least in our experiments—that my whimsical decision-making is paying off (or at least, in the case of reliable roasted vegetables, not doing me any harm). Unless you're roasting something delicate, or looking for particularly blonde slices and chunks, how you line your pan for a standard batch of roast potatoes is not going to make a huge difference.
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When we roasted four similarly-sized, similarly-oiled batches of radishes, turnips, and carrots for Roasted Spring Roots with Horseradish Thyme Butter, we were surprised by how hard it was to deem one tray as being "best-roasted." Try to spot some distinctions in the baking sheets below—it's hard!
But scrutinize the image below, and you may be able to convince yourself of some subtle variations. I did!
The root vegetables baked on the bare sheet tray had the crispest, most burnished edges—they were the most traditionally "roasted-looking."
The batch baked on the parchment were the most uniform in color, with fewer burnt or deeply-colored bits. Compare, in the image below, the turnips—that's the first row—and the carrots—that's the second—that were baked straight on the sheet (first column) versus on parchment (last column). It's easy to see—and understand—how putting a layer of protection between the vegetables and the super hot sheet tray changes how heat is transferred and, consequently, how the vegetables cook.
The vegetables baked on the silicone nonstick mat and on aluminum foil fell in the middle of the (very small) spectrum—somewhere between those cooked straight on the baking sheet versus those protected by a sheet of parchment.
Curious as to whether there exists a standard recommendation, I did a bit of cross-referencing:
In our guide to roasting any vegetable, we recommend parchment paper—no questions asked (or explanation given).
But we've got plenty of recipes in the archives that call for foil or for going totally naked (in terms of lining the sheet, that is). In Merrill's recipe for Crisp and Tender Roasted Root Vegetables, she says to "line a rimmed baking sheet with parchment (or don't if you're lazy like me and don't mind the extra caramelization)." (Hey Merrill, I'm with you!)
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. Just oil the florets or slices and throw them directly on the sheet tray.
What's a home cook—and a lazy-but-picky one at that—to do? Faced with few definitive answers, here's what I've deduced (and I hope you'll share your own findings in the comments below!):
For less caramelization (and easier clean-up), stick with foil, a nonstick baking mat, or—for palest results—parchment paper. All 3 liners serve as a barrier between the heat-conducting baking sheet and your food. But since parchment and silicone are both nonstick, whereas aluminum foil—unless specially labeled—is not, these materials should make for even fewer browning edges and will not require as much oil. (While I didn't notice a difference between the foil- and silicone-roasted vegetables, there were too many variables at play to make a definitive call.)
The first principle comes in handy not only for vegetables you'd like to keep soft all over, but also for delicate ingredients that might burn easily (think thinly sliced onions, mandolined potatoes that you don't want to turn to chips, little baby leeks and radishes, kale leaves). Consider lining the pan, if only to protect them from the baking sheet's extreme heat and secure a little bit of insurance, buying some time between delicious and destroyed. (You'll notice in our first photo that all of our little leeks burned except for those on parchment.)
For anything that's going to be soupy—like watery fruits or vegetables that will release lots of moisture whilst baking (think: tomatoes and strawberries)—the aim is, obviously, not crisp them up. I'd use foil or parchment. You're not aiming for sear—and the liquidy mess will be easier to direct (you don't want to lose those juices and syrups!) on a lined sheet.
But for starchy and hearty vegetables—squash, broccoli, cauliflower, brussels sprouts—where the brownest pieces are the ones you grab first, roast right on your baking sheet. And revel in the results! (Then ready the dish soap.)
When do you line pans for roast vegetables and when do leave them bare? Tell us in the comments below!
A (former) student of English, a lover of raisins, a user of comma splices. My spirit animal is an eggplant. I'm probably the person who picked all of the cookie dough out of the cookie dough ice cream. For that, I'm sorry.