In a large pot of salted boiling water, cook spaghetti according to package directions until al dente. Drain.
Meanwhile, in a large pan over medium-high heat, heat oil. Add chicken and season with salt and pepper. Cook, stirring occasionally, until golden, about 6 minutes, then add onion and peppers and cook, stirring, until soft, 5 to 7 minutes more. Add spices and stir until coated.