In a skillet, brown the ground beef over medium heat. Do not drain.
If using, add the mushrooms, and cook, stirring often, until they are softened and slightly browned.
Add the flour and cook, stirring constantly, until the flour is no longer raw, approximately 2-3 minutes.
Add the Worcestershire sauce, beef base (or crushed beef bullion cube), black pepper, and onion powder (if using), and stir to combine.
Add about 1/2 cup of milk, and stir to combine.
Gradually add the rest of the milk, stirring after each addition. Cook until the gravy is your desired thickness, at least five minutes and up to fifteen.
Notes
The nutrition information includes the mushrooms and onion powder, but does not include the toast and butter.This recipe can easily be doubled or even tripled, depending on how big a crowd you have to feed. You can also serve this over biscuits.