Place a gallon of warm water in a clean bucket or cooler. Add the brown sugar, salt, shallots, garlic, herbs and spices. Stir to dissolve the salt and sugar.
Carefully submerge the turkey in the brine. Add an additional 1/2 gallon of water to make sure the brine covers the turkey entirely. (Or more water!)
If using a bucket, cover the bucket with plastic and place in the refrigerator for 1 to 3 days. If using a cooler, filled it with ice to keep the turkey cold for up to 3 days.
The brine time should be determined based on the size of turkey. For a turkey 15 pounds or under, brine for just 24 to 36 hours. For a turkey larger than 15 pounds, brine for up to 3 days. *If you want to brine a smaller turkey for a longer period of time, reduce the salt to 1/2-3/4 cup, so it is not overly seasoned.
Before roasting, take the turkey out of the brine water and place on a rack for at least a couple hours. Allow the turkey skin to dry thoroughly. Use paper towels to pat it dry if needed. You can place the roasting pan in the refrigerator (or back in the cooler over ice) if you want to give the bird longer to dry. (The dryer the skin, the better it browns. Drying it overnight is best.)
Once dry, rub the turkey skin thoroughly with butter. Sometimes I stuff the turkey with herbs, but this is not necessary.
Roast the turkey at 325° F for 15 minutes per pound. Roast uncovered for the first couple hours, then tent with foil the last hour to make sure the breast meat doesn’t overcook. When using a meat thermometer, the breast meat should be 165° F.
Allow the turkey for rest for at least 25 minutes before serving to allow the juices to redistribute.
If you plan to brine a large turkey for more than 24-48 hours, use 2-3 gallons of water per 1 cup salt, to make sure the turkey doesn't over-season.