Begin by bringing a large pot of salted water to a rolling boil. Add the spaghetti and cook according to the package instructions until al dente, usually around 8–10 minutes. Once cooked, drain the spaghetti in a colander and set it aside.

In a large mixing bowl, combine the shredded cooked chicken with diced tomatoes, barbecue sauce, garlic powder, and salt and pepper. Stir well until all ingredients are evenly coated and blended together.

Preheat your oven to 350°F (175°C). Grease a 9x13 inch baking dish and spread the drained spaghetti evenly across the base.

Pour the chicken and barbecue sauce mixture over the layer of spaghetti in the baking dish and spread it evenly.

Sprinkle the shredded Monterey Jack cheese generously over the mixture.

Place your assembled dish in the preheated oven and bake for 20–25 minutes until the cheese is melted and bubbly.

Remove the dish from the oven and let it cool for a few minutes. Garnish with chopped green onions and fresh parsley before serving.