Prep turkey: Remove the turkey from its packaging and remove any innards from the inside of the turkey. Set aside.
Dry brine: Add the kosher salt, pepper, thyme, and rosemary to a small bowl and mix until combined.
Separate the skin from the turkey meat and rub the salt mixture under the skin of the turkey. Be sure to rub the breasts, legs, and wings. Place the turkey in a large plastic bag or air tight container and refrigerate overnight.
Remove the turkey from the refrigerator and discard any excess liquid. Pat the turkey dry with paper towels and set aside.
Preheat the oven to 400ºF and place a wire rack on a large baking sheet. Alternatively, you can use a large roasting pan.
Spatchcock turkey: To spatchcock the turkey, set the turkey breast-side down on a cutting board and use very sharp kitchen shears to begin cutting down one side of the spine through the ribs and then repeat on the other side of the spine. Discard the spine.
Flip the turkey over onto its breasts and use your hands to press firmly on the center of the bird, flattening the turkey.
Stuff and season: Place the flattened turkey onto the wire rack and stuff the onion and garlic under the skin of the turkey. Tuck the fresh herbs under the wings and season the turkey skin with the turkey seasoning. Massage the seasoning into the skin.
Roast turkey: Drizzle the olive oil over the turkey and massage the oil into the turkey with your hands. Place the turkey into the oven and bake for 20 minutes at 400ºF.
While the turkey is cooking, place all the ingredients for the basting liquid into a saucepan and bring to a boil over medium/high heat. Turn heat to low.
Once the turkey has cooked for 20 minutes, baste the turkey with the basting liquid and bake for an additional 60-70 minutes, basting every 20 minutes until the internal temperature of the turkey at the thickest part reaches 165ºF.
If the turkey skin begins to brown more than desired, place tin foil over the turkey for the last 20 minutes of the bake time.
Remove the turkey from the oven and let it rest for 20 minutes before caving. We recommend saving the turkey drippings for a simple, homemade turkey gravy (see recipe card for details).