Preheat oven to 350 F. Line a rimmed baking sheet with a silicone baking mat.
In a large bowl, toss the bread pieces with the olive oil and garlic salt. Spread in an even layer on the prepared baking dish.
Bake in the oven for 15 minutes (set a timer!), then leave in the oven as it cools down for about 2 hours.
Remove from oven and let cool completely before transferring to storage baggie or container.
STORAGE: Keep sealed in an airtight container and toss on your salad. Use within 5 days. If you won't use them all within 5 days, keep in the freezer until ready to use. Let warm up on the counter for about 15-20 minutes (they will thaw quickly because they are small pieces!)
GLUTEN FREE: Use sliced gluten-free sourdough bread in place of the loaf bread to make homemade gluten-free croutons.