Bread crumbs, Ofenschlupfer or Semmelknödel are the standard recipes I use when I have left over bread. Another good idea for using stale bread is making bread crisps.
They are easy to make and a delicious snack. Preferably I use old rolls as a sliced roll has the perfect snacking size. And if the rolls was a sesame or poppy seed roll they are especially delicious, as the seeds add a delicious nutty flavour.
You can keep the bread crisps quit simple and only seasoned with some salt. Or you use a wild garlic salt or a bit of harrisa to flavour the oil.