1. Boil potatoes until fork tender. Remove from stove and run under cold water.
2. While cooling, add oil, garlic, chili flake and parsley to a skillet and heat on medium. Add onions. Cover and cook under low heat for approximately 15 minutes. Remove from heat.
3. Spray grill with olive oil. Lay flatbread on grill and grill on both sides (total 5 minutes).
4. Top with onions and a layer of potatoes. Sprinkle with rosemary and finish grilling with closed lid until golden brown.