Whisk together the olive oil, lemon juice, garlic powder, salt and pepper in a small bowl. Add the chicken pieces to a large resealable plastic bag and pour the marinade over the top. Seal the bag, removing as much air as possible, and massage the marinade around the chicken to coat evenly. Refrigerate for at least an hour and up to overnight.
Preheat the oven to 400 degrees F.
Remove the chicken from the marinade and transfer, skin-side up, to a large cast-iron skillet. Pour half the marinade all over the chicken in the skillet. Sprinkle the chicken with a generous pinch of salt and pepper. Roast until the chicken is deeply browned, the meat is cooked through and the juices run clear, about 40 minutes. (An instant-read thermometer inserted in the thigh, avoiding bone, should read 165 degrees F.) Remove the chicken to a platter and let rest while you make the sauce.
For the sauce: Melt the butter in a saucepan over medium heat. Whisk in the honey, oregano, garlic, lemon juice and zest and 1/4 cup skimmed drippings from the skillet and bring to simmer. Taste and season with salt and pepper, and if too tangy, add a bit more honey. Pour the sauce over the chicken, then garnish with the pimientos, chopped parsley and lemon wedges and serve.