Combine and simmer 1 hour (add liver last 20 minutes). Strain broth and add water, if necessary, to make 4 cups. Discard everything except meat; chop fine--add some to the broth, but use most of it in a bread dressing or stuffing recipe. Cool broth, then refrigerate until ready to make gravy.
After turkey has been removed from roasting pan, tip pan and let fat rise in one corner. Pour fat into a cup, leaving juices in pan. Measure 16 tablespoons fat and return to pan; whisk in 1 cup flour. Cook, stirring constantly, until bubbly. Stir in 4 cups stock; continue cooking and stirring, scraping baked-on juices from pan, until gravy thickens and boils 1 minute. Season with salt and pepper; stir in a little bottled Kitchen Bouquet to darken, if desired.
