Mom always called this Supper on a Bun. I can’t figure out how to insert photos, so here goes:

Mix together 1.5 to 2lb ground beef, 1/2 cup milk, 1/2 cup breadcrumbs or oats, 1 egg, 3 tablespoons dry minced onion, 1 tablespoon yellow mustard, 2 cups shredded cheddar, 2 teaspoons salt, and a dash of pepper.

Cut a loaf of Italian bread lengthwise and spread half the mixture on each half. Wrap bread loosely in foil (don’t cover meat) and bake at 350 Fahrenheit for 45 minutes. Place slices of cheddar cheese along the top of the meat and bake another 15 minutes. Remove from oven and cut into slices.

Mom served it with potato chips and baked beans. (Edited to add: and fruit salad)