1 3½–4-lb. whole chicken
2 garlic cloves, finely grated
3 Tbsp. (or more) extra-virgin olive oil
1 Tbsp. garlic powder
1 Tbsp. thyme leaves
2 tsp. soy sauce
1 tsp. mild red pepper flakes or ½ tsp. crushed red pepper flakes
1 large red onion, cut into 8 wedges through root end
½ cup dry white wine
1 cup low-sodium chicken broth or water
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.
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.
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).
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.
Serve chicken with onion gravy.