Bring a large pot of salted water to a rolling boil over high heat. Add the elbow macaroni and cook until al dente, about 8-10 minutes. Drain and set aside.

In a large skillet, melt 2 tablespoons of butter over medium heat. Add cubed chicken breasts, season with salt and pepper, and cook for 5-7 minutes until cooked through.

In the same skillet, melt an additional 2 tablespoons of butter and sprinkle in 2 tablespoons of flour, stirring for 1-2 minutes. Gradually whisk in 2 cups of milk and cook until thickened, about 4-5 minutes.

Lower the heat to medium-low and stir in 2 cups of shredded cheddar cheese until fully melted and smooth.

Carefully fold the cooked pasta and sautéed chicken into the cheese sauce, stirring gently for 1-2 minutes.

For a crunchy topping, preheat the oven to 350°F (175°C), transfer to an oven-safe dish, sprinkle with breadcrumbs, and bake for 20 minutes until golden.

Once baked, remove from the oven, let cool slightly, garnish with chopped parsley, and serve in bowls.