In med sauce pan heat milk, salt and pepper to a low boil on med to med high heat. (you need to stir frequently so milk does not scorch.).
Whisk 1/2 cup flour and the 1/2 cup milk to a slurry and slowly stir into hot milk. (at this point you will want to stir constantly as the flour will have a tendency to collect on the bottom of the pan and burn.).
Reduce to simmer stirring constantly for 10 minutes or so until gravy reaches desired thickness. (Simmering will cook the flour and remove the pasty flavor. Gravy will thicken a little more as it cools.).
This is good by itself but you can also add your favorite meat for additional flavor. Serve over your favorite biscuit recipe.