Season the boneless, skinless chicken breasts with salt and pepper. Heat a skillet over medium heat and add a splash of olive oil. Cook the chicken for about 6-7 minutes on each side, or until the internal temperature reaches 165°F (75°C) and the chicken is golden brown. Remove from the heat, let it rest for a couple of minutes, then shred the chicken with two forks.

While the chicken is cooking, bring a large pot of salted water to a rolling boil. Add macaroni and cook according to package instructions, typically around 6-8 minutes, until al dente. Drain the pasta and set it aside, ensuring to leave a little pasta water in case you need it later for adjusting the sauce.

In a medium saucepan, melt 4 tablespoons of butter over medium heat. Once melted, whisk in ¼ cup of flour, creating a roux; cook for about 1 minute. Gradually add in 2 cups of milk while whisking continuously until the mixture thickens, about 3-4 minutes. Stir in garlic powder and onion powder for added depth of flavor.

Lower the heat and begin incorporating the shredded cheddar and mozzarella cheese into the thickened milk mixture. Stir gently until the cheeses melt completely and the sauce becomes creamy and smooth. Taste the cheese sauce and adjust seasoning with salt and pepper if needed.

Add the cooked macaroni to the cheese sauce, stirring thoroughly to coat the pasta. Then, fold in the shredded chicken along with your favorite BBQ sauce, mixing until everything is well combined.

Dish out the BBQ Chicken Mac and Cheese while it's still hot and creamy. For an added touch, drizzle more BBQ sauce on top and garnish with fresh herbs, if desired.