Chop your chipped beef roughly and set it aside. If you are sensitive to salt, rinse the beef.
Melt butter in a small saucepan over medium heat. Whisk in the flour and cook the roux for a minute. Whisk in the milk gradually and season with ground nutmeg, ground onion powder, ground garlic powder, a few drops of Worcestershire sauce, and a squirt of mustard. Cook until thick and season the white sauce with black pepper. Stir in the chipped beef and set the heat to low.
Meanwhile, toast your bread. Once toasted, top with the beef mixture and sprinkle with parsley.