Hamburger Pie/Sheperd's Pie

This is a recipe that I grew up on with a slight variation...my cousin Gayleen adds BBQ sauce to her's...it definitely adds a little zing to a sometimes boring casserole.

1 lb. ground beef
1 md. onion
1 pint jar of tomato sauce (16 oz)
1 pint of green beans (1 can from store)
BBQ sauce ( about 1/2-3/4 cup, just add as much as you like)
Mashed potatoes
Cheddar cheese

I brown the hamburger and the onions, then I add the tomato sauce and BBQ sauce. let simmer until thickness you'd like. Add the green beans to mixture and put in bottom of 9x13 casserole dish. Next layer on the mashed potatoes, the add cheese on top.