Cut the bread into small cubes or tear it into bite-sized pieces. Place the cubes in a medium bowl.
Toss with the olive oil, kosher salt, garlic powder, and a few grinds of black pepper. Line a baking sheet with parchment paper and top with the bread cubes.
Bake until evenly golden brown and crisp, about 15 minutes. Allow to cool for 5 to 10 minutes, which lets them crisp up fully. (Croutons can be made in advance. Allow to cool completely to room temperature, then store in a sealed container for up to 2 weeks.)