Step 1

Preheat oven to 450°. Arrange turkey wings and neck, if using, on a rimmed baking sheet and roast, turning turkey halfway through, until golden brown, about 45 minutes.

Step 2

Transfer wings and neck to a stockpot. Pour off fat from baking sheet; discard. Pour 2 cups water onto baking sheet. Scrape up any browned bits with a wooden spoon. Pour liquid from sheet into pot with turkey. Add onion, carrot, celery, parsley, thyme, peppercorns, bay leaf, and 10 cups water. Bring to a simmer; reduce heat to low and simmer gently until stock is reduced by at least one-third, about 4 hours.

Step 3

Strain stock through a fine-mesh sieve into a clean saucepan. If you have more than 6 cups stock, simmer, uncovered, over medium heat until reduced to 6 cups. Let cool. Pour stock into an airtight container; cover and chill.

Step 4

Do Ahead: Stock can be made 3 days ahead. Keep chilled. Stock can also be frozen for up to 3 months.