Preheat the chicken to 350°. Rinse the chicken off and place chicken breast-side down with the wings facing towards you. Use kitchen shears to cut through the ribs right next to the spine on both sides to remove spine. Open the rib cage and use a heavy chefs knife to score down the sternum. Flip the chicken over with the breast side up and using the palm of your hand, push firmly over the breast bone so the chicken lays completely flat.
Transfer the chicken to a roasting pan and use your fingers to separate the skin and create pockets. Tuck 2 pieces (tbsp) of butter underneath the skin on the chicken breast, on both sides. Coat the chicken in the olive oil and rub the spices onto the chicken on both sides.
Lay the chicken open side down on your roasting pan and roast for 20 minutes on 350° degrees and then continue to roast on 400° degrees for 45 minutes. Insert an instant-read thermometer into the thickest part of the chicken, once the internal temperature registers 160°, it should be done and the skin should be crispy. Remove the chicken and let it rest for 10-15 minutes before cutting.