With Fresh Bread (for fresh breadcrumbs or dried breadcrumbs)
Finely cube the bread and add to a food processor into breadcrumbs. This can take between 30 seconds to 2 minutes (or longer if you have a weak machine).If you want fresh breadcrumbs, then this is all that's needed - use immediately or store for later.
For dried breadcrumbs - once processed, spread the breadcrumbs out over a large oven tray in a thin layer (use two trays if necessary).
Bake in a preheated oven at 300ºF/150ºC for 10-15 minutes, stirring the crumbs halfway. The crumbs are ready when they're lightly browned and feel dry.Allow the crumbs to cool (they will dry further) before using immediately or transferring to an airtight jar.With this process, you can alternatively dry out the bread in the oven first, before processing it into crumbs. However, this takes longer as the larger pieces of bread will take longer to dry, though, and you may need to dry the bread further once it's processed if it isn't fully dry.
With Stale Bread
The bread I used was very hard and dried, so you can break it into pieces and then add it to a food processor to process into the preferred consistency.If the bread isn't really stale/fully dry, it might not process as fine as you'd like. If that's the case, you can dry the crumbs out in the oven (method above), allow them to cool, and then re-process them into a finer crumb.
For Italian Breadcrumbs
For each cup of homemade breadcrumbs using either of the methods above, add 1 tsp dried Italian seasoning, 1/8th tsp garlic powder and onion powder, and 1/4-1/2 tsp salt.Feel free to adjust those amounts to your liking. If you don't have Italian seasoning, you could add some or all of the individual dried herbs (equal to 1 tsp total).
How To Store Homemade Breadcrumbs
Store the prepared dried breadcrumbs in a large airtight jar or container for up to a month. If there is any moisture left in the bread, it may spoil faster, though, so it's important to dry them thoroughly or store them in the freezer (read the FAQs on the blog post).Fresh breadcrumbs (using fresh bread that isn't dried out in the oven) will store for a week in an airtight container in the refrigerator or up to a month in the freezer.
Notes
If you want homemade breadcrumbs with a uniform color, you can remove the crusts first and blend the bread's crusts and interior separately. You can use the crumbs from the crusts and heel of the load within casseroles and meatballs, while the lighter crumbs work well for breading and sprinkling over dishes.
It's important to make sure the breadcrumbs are completely dry if you plan to store them at room temperature; otherwise, the freezer is the best option.
You can experiment with other seasonings too. For example, combining the breadcrumbs with everything bagel seasoning, cayenne pepper, etc.
If you don't often have stale bread, you can keep a 'scrap bag' in the freezer (like I do with veggie scraps when making stock) with the bits of bread you want to save for breadcrumbs until you have enough to go ahead with the process.
If you have a dehydrator, you can use it instead of an oven to ensure the bread is fully dry (important for storing at room temp).