Prepare turkey: Remove from brine, pat dry, and let rest at room temp for 1 hour. Move oven rack to lowest setting.
Mix herb butter: Stir softened butter, lemon zest, and seasonings (or turkey seasoning packet). Preheat oven to 350°F.
Position turkey: Place turkey breast-up on roasting rack in pan.
Loosen skin: Use a spoon handle to gently lift skin without tearing.
Add butter under skin: Spread one-third of herb butter under skin.
Add butter on top: Coat outside of turkey with remaining butter.
Stuff cavity: Add onion + garlic. Tie legs if desired.
Insert a digital meat thermometer into the thickest part of the breast, making sure it does not touch bone. This will help you cook the turkey to the perfect internal temperature.
Roast: Bake until internal temp reaches 165°F in thickest part (~2½–3½ hours). Tent with foil if browning early.
Rest: Let turkey rest 30 minutes before slicing. Reserve drippings for gravy.