Strain roasted turkey pan drippings through a fine mesh sieve. Reserve 2 cups (480ml) of pan drippings. If insufficient, top up with chicken stock. Discard the solids.
In a saucepan, melt butter over medium low heat. Add all-purpose flour and whisk until lightly brown and bubbly, about 2 to 3 minutes. Gradually pour in the reserved pan drippings and whisk to combine with the roux until smooth. Bring to a gentle boil.
Add half-and-half and continue to whisk until smooth. Add ground pepper and salt (if necessary). Drippings may be sufficiently salty, so make sure to taste before adding the salt. Allow gravy to heat through. Turn off stove.
Transfer gravy into a gravy boat and serve with Creamy Mashed Potatoes.