Preheat the oven to 250°F to 300°F
Slice bread into small pieces
Spread the bread pieces on a baking sheet
Bake until completely dry and crisp
Let the bread cool fully
Break the dried bread into smaller pieces
Grind the pieces in a blender, food processor, or spice grinder
Sift the powder if a finer texture is needed
Grind again any larger crumbs
Store the bread powder in an airtight container