Preheat the oven to 400 degrees. For more tooth-friendly croutons, remove the crusts from the bread, then cut the loaf into inch-thick slices. Cut each slice into inch-wide strips. Working in a large bowl, tear croutons directly off the loaf, as long as you get somewhat evenly sized pieces - I find that preslicing speeds up the whole process and yields even, yet rustic-looking croutons, so it's my preferred method.
Toss the croutons with olive oil and 2 cloves of finely grated garlic, 1 tablespoon dried oregano and 1/2 teaspoon red pepper flakes to coat them evenly. Spread them out on a single layer on the baking sheet. Use a second sheet as needed to prevent crowding, which will entrap steam and keep the croutons from browning.
Toast the croutons for about 18 to 22 minutes, checking them after 8 minutes. rotate the pans, switch their oven positions, and use a metal spatula to turn and rotate the croutons so they brown evenly. Once they begin to brown, check them every few minutes continuing to turn and rotate. Some croutons might be done when others still need a few more minutes of baking, so remove them from the tray and let the rest finish cooking. Bake the croutons until they are golden brown and crunchy on the outside, with just a tiny bit of chew on the inside.
Taste a crouton and adjust the seasoning with a light sprinkling of salt if needed. When done, let the croutons cool in a single layer on the baking sheet. Use immediately or keep in an airtight container for up to 2 days. To refresh stale croutons, bake for 3 to 4 minutes at 400 degrees.