Marinate the chicken: In a large bowl, whisk together the oregano, cumin, cinnamon, basil, paprika, cayenne, 2 tablespoons of the garlic powder and 1 tablespoon salt with ¼ cup of the yogurt, 1 tablespoon olive oil and 2 tablespoons lemon juice. Add the chicken to the marinade. Massage the chicken in the marinade, coating completely. Set aside to marinate for 30 minutes, or cover and refrigerate for up to 24 hours.

Meanwhile, make the dressing: Whisk together the dill, mayonnaise, ¼ cup olive oil and the remaining 1 tablespoon garlic powder, ¼ cup yogurt and 2 tablespoons lemon juice in a small bowl. Season with salt and pepper, then set aside.

When the chicken is done marinating, drizzle the remaining 2 tablespoons of olive oil on a grill pan or nonstick skillet over medium high heat. Let the excess marinade drip off the chicken and then cook the chicken, a few pieces at a time, for 5 minutes, flip and cook for another 3 minutes. The chicken should be browned on both sides and cooked though. (Because of the dairy in the marinade, expect it to caramelize a bit in the pan. Turn down the heat if it begins to burn.) Set the chicken aside to rest; it will continue to cook off the heat. Repeat with the remaining chicken. When the chicken is cool enough to handle, chop into ½-inch pieces.

Assemble the salad: Make a bed of romaine in a large salad bowl or serving plate, then create rows of tomatoes, cucumber, onion, chicken, pita chips and crumbled feta. Drizzle with about half of the dressing and serve with the remaining dressing and more feta, if desired, on the side.