Scatter half the sliced onions in the bottom of a roasting pan.
Pat the chicken dry, then rub all over with schmaltz, salt, pepper, and paprika.
Place the chicken on top of the onions in the pan, and scatter the remaining onions over and around it.
Roast 20 minutes, then reduce heat to 350°F (175°C) and continue roasting 55–65 minutes, basting once or twice, until a thermometer in the thigh reads 165°F (74°C).
Rest 10–15 minutes before carving, and serve with the roasted onions.