Strain the turkey drippings from the roasting pan into a measuring glass or small bowl; discard the solids. Let settle, then skim and discard any fat from the drippings.
Melt the butter in a medium saucepan over medium heat. When it bubbles, whisk in the flour and cook for 2 minutes. Pour in the pan drippings and stock, and whisk until combined. Reduce the heat and simmer (stirring constantly) until thickened, 8 to 10 minutes.
Season with salt and pepper.