You can omit the pancetta, but it gives the finished dish a meaty depth that’s worth the extra step.
- Kosher salt, freshly ground pepper
- 4 ounces pancetta, sliced crosswise into ½-inch-wide strips
- 1 pound cipolline onions, peeled
- 1 3½–4-pound chicken, cut into 6 pieces
- 1½ cups low-sodium chicken stock or broth
Preheat oven to 400°. Place flour in a shallow bowl; season with salt and pepper.
Heat oil in a large ovenproof skillet over medium-high. Cook pancetta, stirring, until crisp, about 5 minutes. Transfer to a bowl with a slotted spoon. Cook onions and garlic in skillet until golden brown, 8–10 minutes. Add to pancetta.
Dredge chicken in flour, shaking off excess. Cook in skillet, turning once, until browned all over, 10–12 minutes. Spoon off all but 2 Tbsp. fat from pan and arrange chicken skin side up. Add pancetta, onions and garlic, rosemary, bay leaves, and wine, shaking skillet to disperse liquid. Add stock to bring liquid up the sides of chicken without going over the top (this will keep skin crispy). Bring to a boil, then braise in oven until an instant-read thermometer inserted into the thickest part of breast registers 160° (165° for dark meat), 30–35 minutes.
Transfer chicken and vegetables to a platter; discard herbs. Simmer liquid over medium-high heat until thick enough to coat a spoon, 10–12 minutes. Season with salt and pepper and pour over chicken.
Do Ahead: Chicken can be made 1 day ahead; cover and chill.