Place a medium skillet over medium heat with 2 turns of the pan of EVOO, about 2 tablespoons. Add the onions to the pan and cook slowly, stirring occasionally, until they're deep golden brown, about 30 minutes. If the onions begin to stick to the pan, add a splash of water to loosen them up.
When the onions are almost done, use a large round cookie cutter to cut the crusts away from each slice of bread to make 8 bread discs. Set aside.
When the onions are ready, place a large skillet over medium-high heat with 2 turns of the pan of EVOO, about 2 tablespoons.