Scrape up all the chunks from the bottom of your roasting pan and pour into a saucepan along with the drippings.

Mix together in a coffee mug the flour and milk, making a roux. Stir until it is a wet, pasty consistency. Add more flour or milk, if necessary, in order to attain the proper consistency.

Pour the chicken broth and the sherry into the sauce pan with the pan drippings and whisk over a medium heat until heated through.

Begin adding the roux a little at a time and continue whisking until it thickens to the consistency you desire. Add garlic salt, if needed.

Remove all the chunks by using a strainer to transfer it into a gravy boat. It should be a nice creamy texture.