Heat oven to 350 degrees. Mix beef, bread, milk, egg, onion, Worcestershire sauce and salt. Spread in ungreased 9 inch pie pan. Bake until done (35 to 40 minutes). Top with mashed potatoes, spreading to edges. Sprinkle with cheese. Bake additional 3 to 4 minutes to melt cheese.
You may need to thin potatoes with mik to be able to spread them well, especially if you use leftover potatoes.