Step 1

Place rack in middle of oven; preheat to 425°. Pat chicken dry inside and out and season generously with salt. Mix garlic, oil, garlic powder, thyme, soy sauce, and red pepper flakes in a small bowl.

Step 2

Place chicken in a medium cast-iron or other ovenproof skillet. Smear garlic oil all over outside of chicken. Roast until skin is golden brown all over, 20–30 minutes. Reduce oven temperature to 350°. Continue to roast, rotating skillet if chicken is browning unevenly, until skin is crisp, leg joints wiggle easily, and an instant-read thermometer inserted into the thickest part of breasts registers 155° and the thickest part of legs registers at least 160°, 35–40 minutes longer. Transfer chicken to a cutting board; let rest at least 20 minutes before carving.

Step 3

Meanwhile, set skillet with pan juices over medium heat (wrap a dry kitchen towel around handle), add onion, and cook, stirring often, until softened and golden brown, 8–10 minutes (if the skillet looks dry, add a little more oil).

Step 4

Add wine to skillet and cook, scraping up browned bits, until wine is almost completely evaporated, about 5 minutes. Add broth and cook, stirring occasionally, until gravy looks slightly thickened (it will be a little looser than a regular gravy), 6–8 minutes.

Step 5

Serve chicken with onion gravy.