A perennial problem at my restaurants revolves around leftover croûtons (crostini), which we serve with fish soup. They simple aren’t good enough the next day, so I pulverise them in a food processor to produce olive-oil crumbs.
Make crostini according to the recipe, then when cool (or leftover), whirl briefly in a food processor. Spread out on a baking sheet and sprinkle with a little olive oil and re-bake in a slow oven (140°C/275°F/Gas 1) until golden and crisp. Allow to cool again, then season and whirl again briefly until an even crumb is produced. Do not reduce to a powder.
Various flavourings can be added to these crumbs (pesto, for instance).