Tender Chicken Legs With Schmaltzy Croutons

Name: Tender Chicken Legs With Schmaltzy Croutons
Ingredients: Kosher salt; Freshly ground black pepper; 6 chicken leg quarters (aka whole chicken legs, about 2½ pounds total); 1 medium red onion, unpeeled and quartered through the root end; 1 head garlic, halved crosswise; 1 large lemon, sliced into wheels, seeds removed; 1 handful thyme or oregano sprigs (optional); 1/3 cup cup extra-virgin olive oil; 6 ounces crusty bread, such as country-style miche, baguette, or ciabatta, torn into 1-inch pieces (about 2 cups); Mild chile flake, such as Aleppo pepper or gochugaru, for serving (optional)