Preheat your oven to 300°. Slice your bread into ¼ inch slices and arrange them on a baking sheet in a single layer. Place them on the middle rack in the preheated oven and bake for 15 minutes on each side. After 30 minutes take the sheet out and test the bread for doneness. It should be completely dry and snap or crumble.
Place crisp bread into a food processor and process until they are medium crumbs. I like to keep them a little larger initially because I can always make them finer depending on what I need.