Cook the spaghetti according to package instructions until al dente.
In a large skillet, heat olive oil over medium heat and add chicken.
Season the chicken with garlic powder, salt, and pepper as it cooks.
Once cooked, remove the chicken from the skillet and chop into bite-size pieces.
In the same skillet, add diced tomatoes and BBQ sauce, stirring well.
Add the cooked spaghetti to the skillet along with the chicken, mixing thoroughly.
Stir in shredded Monterey Jack cheese and green onions, mixing until cheese is melted.
Serve hot, garnished with additional green onions if desired.
