Bring a large pot of salted water to a boil. Add the elbow macaroni and cook according to package directions until al dente. Drain the pasta and set it aside.

In a medium bowl, combine the shredded cooked chicken with your favorite BBQ sauce. Stir until the chicken is evenly coated and set aside.

In a large Dutch oven or heavy-bottomed pot, melt the 1/2 cup of butter over medium heat. Once melted and bubbly, whisk in the flour. Cook, whisking constantly, for about 1-2 minutes to form the roux.

Slowly pour the warm milk into the roux, whisking continuously to prevent lumps. Continue to cook, stirring frequently, until the sauce thickens to coat the back of a spoon, about 5-7 minutes. Remove from heat.

Add garlic powder, onion powder, smoked paprika, salt, and pepper to the sauce. Stir in shredded cheeses a handful at a time until fully melted and smooth.

Gently fold the cooked macaroni and saucy BBQ chicken into the cheese sauce until well combined.

Pour the mixture into a 9x13 inch baking dish. In a small bowl, combine panko breadcrumbs and melted butter, then sprinkle over the top. Bake at 375°F (190°C) for 20-25 minutes until bubbly and topping is golden. Let rest for a few minutes before serving.