Once you have roasted a turkey, pour the remaining juices from the roasting pan into a glass measuring cup. Allow the fat to separate, about 10 minutes. Pour off the fat.
Place the roasting pan over two burners on medium heat. Simmer the wine, stirring and scraping the bottom of the pan constantly. Add the juices from the turkey and four cups of chicken stock and simmer.
Whisk together the remaining half cup of chicken stock with the flour until smooth. Slowly add the flour mixture to the roasting pan. Simmer until gravy is reduced by half and coats the back of a spoon.
Remove from heat and add butter. Lightly whisk until the butter has melted.
Pour the gravy through a fine sieve and discard the solids. Serve warm.