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

In a large skillet, melt 2 tablespoons of butter over medium heat. Add diced chicken, season with salt and pepper, and sauté for 5-7 minutes until golden brown.

Add another tablespoon of butter to the skillet, then sprinkle in the flour and whisk until a smooth paste forms. Gradually incorporate milk and cook until thickened.

Reduce heat to low and add shredded cheddar cheese to the mixture, stirring until melted and smooth.

Fold the drained macaroni and sautéed chicken into the cheese sauce until evenly coated.

Transfer to an oven-safe dish, sprinkle breadcrumbs on top, and bake at 350°F (175°C) for 20 minutes or until golden.

Garnish with chopped parsley and serve warm.