1. Pour pan juices through a fine sieve into a glass measuring cup, and skim off fat. Let stand for 5 minutes, then skim off fat again.

2. Return pan juices to roasting pan. Set pan across 2 burners over medium heat. Bring to a simmer, and cook, scraping up browned bits with a wooden spoon, for 2 to 3 minutes.

3. Whisk together 1/2 cup stock and the flour in a small bowl until smooth. Add remaining 3/4 cup stock to pan juices. Bring to a simmer. Whisk in flour mixture, and return to a simmer. Cook until mixture thickens, 4 to 5 minutes. Add more stock if gravy is too thick or too salty. Whisk in butter to finish. Serve warm.