Tear the bread into pieces, then grind in a food processor until coarsely chopped; you may have to do this in batches.
Use immediately or store in a plastic bag.
To toast, put the bread crumbs on a baking sheet and place in a 350F oven, shaking the pan occasionally, until lightly browned, about 15 minutes; these may be stored as fresh (though it makes more sense to store untoasted bread crumbs and toast just before using).
Or heat 1/4 cup extra virgin olive oil in a skillet and add the bread crumbs; cook, stirring occasionally, until lightly browned, about 5 minutes.
Season with salt and drain on paper towels; use immediately.