Cut the loaf into cubes and transfer them to a bowl. Top with olive oil, garlic, rosemary and sea salt. Toss to combine.
Transfer the bread cubes to a baking sheet. Bake for 25 - 35 minutes, flipping halfway through. Watch them carefully so they don't burn.*
Allow croutons to cool completely, then store in a sealed container and use for up to 1 week.
* if the crounts are getting brown too quickly and not crisping up, turn the oven off and let them cool in the oven with the door propped open for 1 - 2 hours.** nutrition value will differ based on the bread you use.