Preheating the oven is, for the most part, a scam. Unless you’re baking a recipe that includes some sort of leavening agent, you’re wasting the energy being expended by your oven as it works to reach its target temperature. In some cases, gently heating your food along with the oven even offers a few benefits. One of those cases is bacon; another one is chicken, especially chicken thighs.
Much like bacon, chicken thighs contain a good deal of fat. Unlike bacon, they also contain a lot of connective tissue, mostly collagen. Both fat and collagen do best with a prolonged, slow cook, which gives that thick layer of fat under the skin time to render out, resulting in crispier skin. It also gives the collagen time to melt into gelatin, resulting in a juicier, richer tasting bird.
It’s also faster, because you don’t have to wait for the oven to “reach temperature.” All you have to do is marinate, brine, or season your thighs however you usually would, then place them in a cold, greased pan or skillet. Place that skillet in a cold oven, and set the temperature to 375℉. The slowly increasing heat will gently cook the chicken, render out the fat, and melt all that wonderful collagen.
After half an hour, temp the chicken with a thermometer. You want a temperature of 170℉, so keep cooking until you reach it. (It shouldn’t take much over half an hour, but I shy away from giving an exact cooking time here, because ovens—and how they preheat—are so wildly inconsistent.) If the skin isn’t as crispy as you please by the time it reaches that temp, go ahead and pop it under the broiler for a few minutes. Serve immediately (and save any leftover chicken skin for cracklins).
