In a medium saucepan, melt butter and whisk in flour.
Cook over medium-high heat until flour is incorporated and white bubbles begin to form on the top of the roux.
Cook the roux for 2-3 minute after the white bubbles have formed, whisking constantly.
Gradually add the broth, whisking constantly until the gravy is thickened and comes to a boil.
Remove from heat and season with salt and pepper.
At this point, you can cool, cover and refrigerate the gravy base for as long as 4 days. Reheat in a medium-sized pan. When turkey is done, skim off fat and pour drippings into gravy base and bring it to serving temperature.
