Preheat an oven to 300 degrees F (150 degrees C).

Push torn pieces of bread through the shredding disk of a food processor to make coarse crumbs. Spread the crumbs on a baking sheet.

Bake in preheated oven until crumbs are dry but not toasted, 6 to 8 minutes. Shake the sheet twice during baking in order to evenly dry crumbs. Remove from the oven and cool completely.