Season the chicken breasts with salt and pepper. Heat a skillet over medium heat and cook chicken for 6-7 minutes on each side until golden brown. Remove from heat, let cool, and shred into bite-sized pieces.

In a large pot, bring salted water to a boil. Add elbow macaroni and cook according to package directions for 7-8 minutes until al dente. Drain and set aside.

In a medium saucepan, melt butter over medium heat. Whisk in flour and cook until light golden. Gradually add milk while whisking to avoid lumps. Cook until thickened, about 3-4 minutes, then stir in garlic and onion powder.

Reduce heat to low and mix in cheddar and mozzarella cheeses until melted and smooth. Season with salt and pepper.

In a large mixing bowl, combine cooked macaroni, shredded chicken, and BBQ sauce. Pour cheese sauce over and stir until well-coated.

Serve hot, garnished with fresh herbs and extra BBQ sauce if desired.