Cut bread into cubes. This is most easily done by slicing the bread as normal, then stacking a few slices and cutting them into long strips, then cutting the strips into cubes.
Spread out the bread cubes in an even layer onto a sheet tray.
Drizzle the bread cubes with the olive oil, salt, pepper, garlic powder, and parmesan cheese.
Toss the bread crumbs so they are evenly coated.
Bake in the oven until they are crisp and golden brown, about 30-35 minutes.
Let cool before dressing a salad with them. Store in an airtight container.
Notes
A hearty artisan-style bread works best. You can also use sourdough if you have it.