Sprinkle with 1 teaspoon salt and 1/2 teaspoon pepper, put it in a large roasting pan breast side and brush evenly with melted butter.
Bake in a preheated 400º F oven for 30 minutes.
Do not open the oven but lower the heat to 325º F and bake for 1 hour.
Baste the turkey with the drippings and cook for another hour.
Repeat basting the turkey every hour and cook at 325º F for an additional 1 1/2 hours, or until the thickest part of the turkey breast reads 165º F with a meat thermometer. *Please see notes for proper thawing, roasting and storing leftover turkey.
Remove from oven and cover the turkey with foil and allow to rest at room temperature for 30 minutes before slicing.
Strain the turkey drippings and put the stock back into the roasting pan. Add 2 cups turkey broth and heat over high heat until boiling.
Add the flour and water to a container fitted with a tight lid and shake until well combined. With a whisk, add the flour-water mixture, stirring until the gravy comes to a simmer. Whisk and cook until gravy is thick and creamy.
A 12-18 lb turkey should take approximately 4 hours to cook thoroughly. But, always check the turkey package for full thawing and cooking instructions.
For the gravy, start with 1/2 tsp salt, stir, and taste, then add more if needed.
To keep the turkey slices warm and juicy, cover the bottom and sides of a large baking dish with foil and place the turkey slices in it. Drizzle 1-2 cups turkey broth over the turkey slices, cover with foil and place the baking dish in a warm oven at 200º F until ready to serve.
Nutritional information is approximate depending on light or dark meat and includes a serving of gravy too.