Preheat your oven to 190°C (375°F). Grease a 9x13 inch baking dish.
Cook the macaroni in a large pot of salted boiling water according to package directions, cooking it until it is al dente. Drain well and set aside.
In a small bowl, combine the bread crumbs and melted butter. Set aside.
In a large saucepan or pot, melt the butter over medium heat. Whisk in the flour and cook for 1-2 minutes, stirring constantly, to create a roux.
Slowly pour in the milk, whisking continuously to prevent lumps. Bring the sauce to a simmer and cook for about 5 minutes, until it has thickened.
Remove the pot from the heat. Stir in the grated cheddar cheese, salt, pepper, and dry mustard until the cheese is completely melted and the sauce is smooth and creamy.
Add the drained macaroni to the cheese sauce and stir to combine everything evenly.
Pour the macaroni and cheese mixture into the prepared baking dish. Sprinkle the bread crumb topping evenly over the top.
Bake for 20-25 minutes, or until the topping is golden brown and the sauce is bubbly around the edges.
Let the dish rest for a few minutes before serving. Enjoy!