Cook the macaroni using package directions; drain.
Preheat the oven to 400℉. Place a rack on the lower-third rung in your oven. Spray 2½- quart baking dish with cooking spray.
Melt butter in a large saucepan over medium heat. Whisk in the flour. Cook until smooth and bubbly, stirring constantly. Whisk in the milk, cream cheese, Dijon mustard, salt and pepper. Cook for 3 to 5 minutes or until thickened, stirring constantly. Stir in the cooked pasta and cheddar cheese.
Spoon the cheesy macaroni into the prepared baking dish.
In a small bowl, mix the topping ingredients. Sprinkle the topping evenly over the top of the cheesy macaroni. Bake for 20 minutes, or until golden brown.