In a small mixing bowl, combine olive oil, harissa powder, lemon juice, smoked paprika, cumin, and cayenne pepper. Stir the mixture until a thick paste forms.

Take the boneless chicken thighs and rub the prepared spice paste thoroughly over each piece. Allow the chicken to marinate for at least one hour at room temperature.

While your chicken is marinating, preheat your oven to 425°F (220°C) to ensure even cooking.

Line your baking tray with aluminum foil or parchment paper and place the marinated chicken thighs in a single layer.

Slide the baking tray into the preheated oven and bake the chicken thighs for 18-20 minutes until the internal temperature reaches 165°F (75°C).

Once baked, remove the chicken thighs from the oven and let them rest on the tray for at least 5 minutes before serving.