Cook the macaroni according to package instructions until al dente, then drain.
In a large saucepan, melt the butter over medium heat.
Add flour, garlic powder, onion powder, salt, and black pepper to the melted butter, and whisk until well combined and bubbly, about 1 minute.
Slowly whisk in the milk, continuing to cook and stir until the mixture thickens, about 3-5 minutes.
Reduce heat and stir in cheese until melted and smooth.
Combine the cooked macaroni and shredded chicken with the creamy cheese sauce, stirring until well coated.
If using, transfer the mixture to a baking dish, sprinkle with breadcrumbs, and bake at 350°F (175°C) for 20-25 minutes until bubbly and golden.
Let cool for a few minutes before serving.
