Pound each chicken thigh to about ½ inch thick. Set aside.
Finely mince the garlic and juice the lemon. Add to a large bowl with the olive oil.
Add all spice and stir to combine.
Add the chicken to the marinade and toss to combine, making sure that the chicken is coated.
Cover and refrigerate for 24 hours.
Remove the chicken from the refrigerator an hour before ready to cook.
Preheat the oven to 375°.
Slice the onion in half and place the cut side of one half down in a baking dish.
Take a wooden skewer and push it into the center of the onion. Layer the chicken on top of the onion so that the skewer goes through the center of the thigh. Off set each thigh so that it layers hang on all sides of the skewer.
Place the other half of the onion on the top of the skewer so that the cut side is facing the chicken.
Place in the oven and bake for about 1½ - 2 hours, or until cooked through.
Let cool for 10-15 minutes.
Shave the chicken using a sharp knife.