Bring a large pot of salted water to a rolling boil. Add elbow macaroni and cook until al dente, about 7-8 minutes. Drain and set aside.

In a large skillet, melt 2 tablespoons of butter over medium heat. Add cubed chicken breast seasoned with salt and pepper. Cook for 5-7 minutes until golden brown and cooked through.

In the same skillet, melt 2 tablespoons of butter, then stir in flour and cook for about 1 minute. Gradually whisk in milk, stirring for 4-5 minutes until the sauce thickens.

Reduce heat to low, add shredded cheddar cheese, and stir until melted and creamy.

Fold in elbow macaroni and sautéed chicken, stirring gently to coat everything in the sauce for about 1-2 minutes.

For a crunchy topping, place mixture in an oven-safe dish, sprinkle breadcrumbs on top, and bake at 350°F (175°C) for about 20 minutes.

Let cool for a few minutes, garnish with parsley if desired, and serve warm.