In a small bowl add the olive oil and seasoning and set aside.
Butterfly the chicken breasts and place in a large bowl. drizzle the olive oil mixture over the chicken and mix together and leave to marinate for at least 1 hour, overnight is best.
Preheat the oven to 180℃
Prepare your vertical skewer by placing half a onion at the bottom (cut side down), then start to stack the chicken on top, rotating the chicken so that it's staggered. Top with the other half of the onion.
Place in the oven and cook for approximately 1½ hours.
When the chicken's cooked (internal temperature should be 74c), remove from the oven, leave to cool for around 10 mins and then slice vertically, place on top of your flatbread with salad, chips and sauce of your choice.
