Pat the chicken dry with paper towels and place it on a cutting board, breast side down.
Use sharp kitchen scissors to cut through the small bones on one side of the backbone, staying as close to the bone as possible. Repeat on the other side and remove the backbone from the chicken.
Turn the chicken over so that it is breast-side up. Place one hand between the two breasts and firmly push down to break the breast bone. (You should hear a small crack).
Carefully run your fingers underneath the skin of the breasts and thighs to separate it from the flesh. (Be careful not to tear the skin.) Transfer the chicken breast-side up to a rimmed baking sheet lined with aluminum foil. Tuck the wings behind the breasts and point the legs inward toward each other.
In a small bowl, stir together the salt, thyme, garlic powder, pepper and paprika. Rub about two-thirds of the spice mixture evenly underneath the skin of the breasts and thighs, massaging it into the flesh.
Brush the chicken with olive oil, then sprinkle it with the remaining one-third of the spice mixture. Rub the spices into the skin of the chicken so that they are evenly distributed.
Preheat the oven to 450°F. Let the chicken rest at room temperature for 20 to 30 minutes while the oven preheats.
Divide the butter into 4 pieces and place a piece over top of each breast and thigh.
Roast for 20 minutes, then decrease the temperature to 400°F. Roast for another 20 to 25 minutes until the chicken's internal temperature reaches 165°F in the thickest part of the breast and the juices run clear.
Let the chicken rest for 10 minutes before carving and serving.
Notes
Pat the chicken very dry before seasoning. This will ensure perfectly crisp skin. If you have time, try removing the chicken from its packaging, patting it down with paper towels, seasoning as directed, and then returning it to the fridge uncovered for 12-24 hours for the skin to cure for even crispier results.
Make sure your kitchen shears are very sharp. You'll be cutting through some bones, and contrary to what you might think, dull blades are considered more dangerous than sharp ones because they require you to exert more pressure and can easily slip from their intended position.
Don't toss the backbone! Save it and the leftover chicken carcass for making homemade chicken stock. (You can use my turkey stock recipe as a template.)