Sheet pan dinners are a wonderful and simple way to prepare an easy roasted meal using just a single pan in the oven. The beauty of sheet pans is that they're shallow, which means sheet pan dinners give you all the convenience of a casserole while producing the kinds of caramelized roasted goodness that casseroles can't achieve.
Choose the Best Sheet Pan
For most home cooks, the best sheet pan to use for a sheet pan meal is either a half sheet (18 x 13 inches) or a quarter sheet (9 x 13 inches). Using a half sheet means you'll probably have empty space, but this will end up working better since it improves air flow and promotes better roasting (as opposed to steaming). Get a heavy (18-gauge) aluminum one with rolled rims and—most importantly—no nonstick coating.
On the topic of tools, a metal spatula will be very useful for turning items on the sheet pan without stripping off their outer layers. Tongs won't work as well, nor will plastic or silicone. But don't worry about scratching your sheet pan—they're built to take all kinds of abuse.
Many sheet pan meals involve layering ingredients, with veggies and starch on the bottom and protein (like chicken or fish) on top. There's no real reason for stacking the foods up this way and ideally you won't completely cover your bottom layer—that's where a bigger sheet pan comes in handy.
The issue with layering is that it produces steam and rather than the chicken (let's say) cooking directly against the hot aluminum, it's sitting on layer of vegetables instead. The potatoes underneath your chicken will also end up soggy rather than crispy.
In general, delicate items like fish will work better as a top layer, but chicken and pork will do better when cooked directly on the pan, situated slightly away from the other items.
Coordinate Cook Times
Whether you go for layers or not, sheet pan meals will involve a degree of timing and coordination. Not every items cooks at the same rate, so if everything is going into the same oven at a single temperature, it can't do so at the same time, especially if you want it finished together, which is usually the goal with a sheet pan meal. If you're cooking bone-in chicken parts, it's important to make sure the other items won't be over- or undercooked.
Strive for Contrasts!
You know how food takes on a lovely golden-brown color when you roast it in the oven? This is nice, no question. But when every single component of your meal comes out with the exact same shade of browning, the same crispy exterior, the same fall-apart tenderness, your palate and your eyes are going to start craving some sort of contrast.
To some extent, you can achieve this by opting for brighter colors. Instead of potatoes, cauliflower, or cabbage, consider broccoli, Brussels sprouts, red or orange bell peppers, carrots, and so on. And even then, you're still going to end up with a plate of assorted roasted foods. If nothing else, you can always liven things up with a salad on the side.
Do the Prep in a Bowl
Have you ever tried to toss a salad on a sheet pan? It doesn't work—unless you're trying to decorate your floor with lettuce. The same principle applies here. Just because you're cooking everything in one pan doesn't mean you have to do all your prep in that pan. After all, the thing that makes a sheet pan so well suited for roasting—its low sides—is exactly what makes it terrible for tossing cut up items in olive oil, salt, and other seasonings.
Fortunately, you have bowls. Go ahead and toss, season, and adorn your food in a generously sized mixing bowl, then transfer it to the sheet pan for cooking.
Presear on the Stovetop
As with the bowl, just because you're cooking on a sheet pan doesn't mean you have to do all your cooking on a sheet pan. Remember the issue of steaming as it relates to layers? Steaming won't brown your chicken! But that doesn't mean you can't your chicken or pork some color in a skillet on the stovetop before transferring it to the sheet pan.
Use the Right Protein
Just like no one makes a steak casserole, it's a protein that won't fare especially well as a sheet pan dinner. Yes, you can cook a steak in the oven, but not on a bed of vegetables. The vegetables produce steam and a steamy environment is not a good one for steak. They need dry heat, otherwise they won't brown.
While browning the steak and then finishing it in the oven is a perfectly sound cooking technique, again this assumes that you're not placing the steak directly atop a pile of vegetables. The temperature will cook the steak all right, but it's the steam from the vegetables that will give your steak a soggy bottom.
Chicken, sturdy fish like salmon and cod, as well as pork (especially pork tenderloin), will work best.