1. Heat the oven to 400 F.
  2. If the bread isn't sliced, cut it into slices 1/2 inch thick to get 8 or more slices.
  3. Smear 1 side of each slice with butter or brush with olive oil.
  4. Cut each slice into halves, quarters, or large or small cubes.
  5. Spread the bread out in a single layer on a baking sheet; if they touch a bit, that's fine, but don't overlap them.
  6. Put the pan in the oven and toast the bread, turning the slices or tossing the cubes as needed, for 10 to 20 minutes, until all the sides are lightly browned, depending on how thick the pieces are.
  7. Let cool to room temperature and serve right away or store in an airtight container for up to several days.