Best Turkey Brine

A friend of mine swears by this turkey brine.  She has family members who never cared for turkey until they tried her recipe.  If you’re looking to give your turkey and extra “oomph”, here’s the way to do it.  This particular recipe is for a 15-pound turkey.
For the Brine:
2 1/2 gallons water
2 1/2 cups kosher salt (we use 1 cup)
1 cup maple syrup (we use a half a cup)
12 bay leaves
1/4 cup peppercorns
For the Turkey Prep – Day of:
1 head garlic, broken up
1 stick butter, softened
1 pkg. rosemary
1 T dried thyme
1T dried sage
2 lemons, cut up
1 onion cut up
3 carrots (optional)
Two days ahead (or up to 4 days ahead):
Put water, salt, syrup, peppercorns and bay leaves in a 5 gallon stockpot, cover and bring to a boil.
Stir to help dissolve salt. Remove from heat and let cool. Refrigerate overnight.
One day ahead:
Place 15lb. fresh or freshly thawed (not frozen) turkey in the brine and refrigerate 12 to 24 hours before roasting turkey.
Day of:
Remove turkey from brine and discard the brine. Rinse turkey and pat dry.  Loosen the skin from the neck on each side of the breast to create a pocket to place herbed butter in. Cover turkey under the skin and all over it with herbed butter.  (For herbed butter, mix the butter with the thyme, sage and rosemary plus a few grinds pepper.)
Sprinkle with Salt and pepper.  Place lemon, orange, onion and head of garlic along with some fresh thyme inside the cavity.
 
(Optional) Roughly break up a few carrots, celery and quarter one onion and spread in the bottom of a roasting pan.  Set turkey on top and cover entire pan tightly with heavy duty foil.
Roast for 2 hours at 325 undisturbed.  Then remove foil and continue baking for allotted necessary time (using the rule of 20 minutes per pound, and subtracting the 2 hours you’ve already cooked it for) until golden brown and the thighs reach 170 degrees.  Let the turkey rest with foil tented over it for 30 minutes before slicing.