• Let the turkey thaw in the refrigerator. Remove the neck and giblets, rinse and pat dry. Combine salt and brown sugar in a small bowl and combine with your fingers. Rub it all over the turkey, inside and outside. Place on a rack in a roasting pan and chill, UNCOVERED, for at least 12 hours but up to 24 hours. Remove from the refrigerator an hour before placing in the oven.
• Rinse the turkey and the roasting pan. Use your fingers to loosen the skin and work the softened butter under the skin. Rub some of the butter on the outside of the turkey. Place thickly sliced onions on the bottom or the roasting pan. Place the turkey on a wire rack on top of the onions and cover with foil.
• Bake at 350º for 3-6 hours until a meat thermometer in the thickest part of the breast and thigh reaches 150º. Let it rest, still covered, for at least an hour where it will continue to cook and reach 165º.

Gravy

• When ready to serve, remove the turkey and drain the sauce through a colander to remove the onions. Let it sit for a minute for the fat to float to the top. Remove the fat.
• If your roasting pan can go on the stove, use it. If not, use a medium saucepan. Add 3 tablespoons of butter and heat over medium heat, scraping up any bits from the bottom of the roasting pan. Add flour and whisk for about a minute. Slowly add the turkey juices and whisk until smooth and thickened. Add salt and pepper if needed.