Preheat oven to 450" and adjust rack to middle position. Spray a sheet pan with cooking spray.
Cut up a whole chicken into parts, place back, giblets, and scraps into a stockpot if you're making broth.
Wash veggies and peel beets, turnip, potatoes, and carrot. Cut veggies into uniform cubes and cut onion and fennel into wedges.
Place all vegetables and chicken onto the sheet pan, drizzle with olive oil, dust with seasonings, and toss together to distribute. Spread veggies evenly over the pan with the chicken pieces on top of the veggies.
Put the sheet pan in your preheated oven and roast for 20 minutes.
Check the chicken and vegetables after 20 minutes, shake the pan to prevent sticking. Check the temperature of the chicken with an instant read thermometer. Breast meat should be 165, dark meat should be 175 degrees. If the chicken isn't up to temperature yet, roast for another 10-20 minutes checking every 10 minutes.
Pull the chicken out as soon as it reaches safe temperature, lightly tent with foil and if the veggies are not yet tender, continue roasting until a fork can easily be inserted.