Slice bread, if it isn't already sliced and set bread out for a few hours and allow the slices to become slightly dry. This helps when cutting the bread into cubes. If you use really fresh bread, the cubes become slightly mushed when slicing.
Slice bread into cubes. I usually do about one inch cubes. They don't have to be perfect.
Place cubes in a large roasting pan
Put in a 200°F oven until fully dried, stirring the bread cubes every 30-45 minutes. This process takes anywhere from 2-4 hours, depending on the amount of cubes you are drying.
Once you have determined the cubes to be fully dried, turn off the oven and let the cubes remain in the oven for an additional 30 minutes.
Notes
You can dry any amount of bread cubes. Determine how much you will need for your recipe and dry the appropriate amount.
Stir bread cubes every 30-45 minutes. I use my hands and just rotate the bread cubes around.
The best way to determine if your bread cubes are fully dry is by testing with your hands. If the bread cubes have any give to them, they need to be dried longer.
The bread cubes do diminish in size by about half once they are dried.
Store dried bread cubes in an airtight container. I often reuse the bags the loaves of bread came in.