If using dried garbanzo beans, cook until tender then drain well. If you opt to use canned beans, they will also need to be rinsed and drained well. Transfer the beans to a bowl and stir in the olive oil and za'atar spice mix.
Preheat oven to 350 degrees. After you have drained the beans, spread them singly on a parchment-lined baking sheet.
Bake until golden brown, about 30 minutes. Gently shake the pan every 10 minutes or so for more even browning.
If desired, the garbanzo beans can be lightly salted. (When I cook with za'atar I never add salt.)