Preheat oven to 60°F (or the lowest your oven goes) or 300°F. Line a large baking sheet with parchment.

Remove crusts from bread. (I like to turn those into croutons)

In a blender or food processor pulse bread in batches to get large crumbs.

Spread out the crumbs on the prepared baking sheet and place in oven for about 1 hour at 60°F or 5 minutes at 300°F until dry and toasted but not brown.

Store in airtight containers until ready to use.