Grease a good sized baking dish and preheat oven to 375.
Take 2-3 potatoes and slice them into thin rounds with a mandoline or knife. Place the slices in a bowl of water so they don't brown. Also, slice up a small onion.
Place a layer of spaghetti sauce or seasoned diced tomatoes in the bottom of the dish. This would work very well. Add a layer of potato slices, a layer of onion, and a layer of Italian sausage (raw or cooked, mine was raw and it added a nice flavor). Add another layer of potatoes, then another layer of sauce. Top with Italian breadcrumbs and bake for 1 hour covered, 30-45 minutes uncovered.