Stir the breadcrumbs and milk together and let them stand for 5 minutes until the milk is absorbed.
Mix in the beef, onion, eggs, Worcestershire, salt and pepper just until combined, then shape the mixture into one free-form loaf on a rimmed sheet pan.
Bake at 350°F for 55 to 65 minutes until the center reaches 160°F, then rest for 15 minutes before slicing.
Melt the butter in a saucepan, stir in the flour for 1 minute and whisk in the broth until smooth.
Simmer the gravy for 5 minutes until it coats a spoon and serve it over thick meatloaf slices.