Bring a large pot of salted water to the boil over medium-high heat.
Add the spaghetti and cook for 8 minutes then reserve 1 cup of the cooking water and drain.
In a large skillet or frying pan set over medium-high heat, sauté the peppers, onion and garlic for a few minutes until softened then add the spices and cook for another minute.
Combine the sauteed vegetables with the spaghetti, shredded chicken and béchamel sauce then stir until combined.
Transfer the mixture to a large baking dish/casserole dish and top with the cheese.
Place the dish in the oven and allow to bake for 20 minutes until the dish is hot and bubbling and the cheese has melted.