1. Preheat broiler to high. Soak 24 toothpicks in a small bowl of water for 15 minutes. Mist a large, rimmed baking sheet with cooking spray and place a wire rack on top.
2. Halve prunes lengthwise, taking care not to cut all the way through. Place a small amount of cheese in center of each prune, in cavity left by removed pit. Wrap each prune with bacon, securing with toothpick.
3. Broil for 10 to 12 minutes, turning halfway through.