After roasting the turkey, use a turkey baster to pull out about one cup of the pan drippings, and squirt it into a large measuring cup. Set aside to let the fat rise to the top.
Skim off 1/4 cup of the fat and add to a medium sized saucepan over medium heat. To skim, tilt the measuring cup, and spoon of the oil layer at the top.
When the fat is hot, sprinkle in the flour, and cook while stirring, for a few minutes until golden in color, about 2 minutes.
Skim and discard any remaining fat from the measuring cup, and add turkey stock or water to measure 2 cups. To prevent lumps, is important that the drippings mixture is still warm before adding to the roux. If it has cooled down, heat it briefly in the microwave.
Gradually add to the saucepan and whisk constantly to combine and prevent lumps.
Add the poultry seasoning, bring to a boil over medium-high heat, and continue to whisk and cook until thickened and bubbly, about 5 minutes.
Season with salt and pepper, and keep warm until you are ready to serve. Makes about 2 cups of gravy, about 8 servings.