Do try and get turkey necks for they will give you the richest gravy.
The turkey may be done on top of the stove or in the oven with equally good results.
Terry's Make Ahead Turkey Gravy
8 Turkey necks
4 Turkey Wings -- cracked into a couple of pieces
5 tablespoons Vegetable oil
1 Bay Leaf
10 Black peppercorns
3 rib Celery
2 Onions -- quartered
5 quarts Water -- cold
If using turkey wings, halve at joints with a cleaver or large knife, then crack wing bones in several places with back of cleaver or knife. The Turkey necks will add a gelatinous quality to your stock
Heat 1/4 cup oil in an 8- to 10-quart heavy pot (see cooks' note,
below) over moderate heat until hot but not smoking. While oil is heating, pat turkey parts dry. Cook turkey in 4 batches, turning once, until a good dark brown, 8 to 10 minutes per batch, transferring to a large bowl. Add browned turkey and onions and remaining ingredients to pot and bring to a boil over high heat, skimming froth as necessary. Reduce heat and gently simmer, partially covered, 3 hours.
Remove pot from heat and cool stock
to room temperature, uncovered, about 1 hour. Pour stock through a large fine-mesh sieve into a large bowl and discard solids.
Refrigerate overnight. Next day remove fat from the top of stock and use that to make your roux with equal amounts of flour. Cook for a few moments and gradually add the warmed stock while whisking to keep smooth. Add salt and pepper to taste and if you like you can enrich the gravy with a splash of cream or milk.
After you have roasted your turkey you can save that pan to make additional gravy for the leftovers since you can never have too much gravy.
Stock can be chilled up to 1 week or frozen in an airtight container 3 months.