Stir together the cumin, salt, and cinnamon in a small bowl, and sprinkle them over the chicken. Heat the oil in a large skillet on medium. Add the chicken and cook about 8 to 12 minutes or until done, turning once.
Meanwhile, prepare couscous according to the directions on the package.
Transfer the chicken from the skillet to a serving platter. Then start cooking the baby spinach in the same skillet, stirring it often, for 1 to 2 minutes, or until it begins to wilt. Blend in the cooked couscous. Serve the couscous and spinach as a side dish with the chicken.