Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a small bowl, mix together the harissa paste, honey, olive oil, garlic powder, onion powder, smoked paprika, salt, and pepper until well combined.
Place the chicken breasts on the prepared baking sheet. Brush the harissa mixture generously over both sides of the chicken.
Bake the chicken in the preheated oven for 20-25 minutes, or until the internal temperature reaches 165°F (75°C). Remove from the oven and let rest for 5 minutes before slicing.
While the chicken is baking, prepare the quinoa according to package instructions if not already cooked.
In serving bowls, layer the cooked quinoa, baby spinach, cherry tomatoes, cucumber, and sliced chicken.
Drizzle with tahini dressing and sprinkle with crumbled feta cheese and fresh parsley.