Preheat the oven to 400°F.

Rinse the chicken, pat dry, and remove any excess fat. Sprinkle generously with salt and pepper to taste inside and out. Place the onion and rosemary inside the cavity and rub the outside of the chicken with the paprika.

Lay a standard-size brown paper grocery bag on its side and place the chicken inside, tying the top of the bag closed with kitchen string. Place the bagged chicken on a rimmed baking sheet in the lower third of the oven, so you have plenty of room at the top. Cook for 1 1/2 hours.

Remove the chicken from the oven, and carefully open the bag to release the steam. Check for doneness by inserting a thermapen in the thickest part of the thigh; it should read about 165°F.

Let rest for about 10 minutes before carving. Slice the breasts and cut the wings, legs, and thighs into pieces. Serve warm.