Instructions:

1. Cook the macaroni pasta in a large pot of salted boiling water according to the package instructions until al dente. Drain and set aside.
2. In a large saucepan, melt the butter over medium heat. Add the flour and cook, stirring constantly, for about 1-2 minutes until it forms a smooth paste (roux).
3. Gradually whisk in the milk and heavy cream, continuing to stir until the mixture is smooth and begins to thicken.
4. Stir in the mustard powder, salt, and pepper.
5. Gradually add the shredded cheddar and mozzarella cheeses, stirring constantly until the cheese is melted and the sauce is smooth.
6. Add the cooked macaroni pasta to the cheese sauce and stir until well combined.
7. Optional: Preheat the oven to 180°C (350°F). Transfer the mac and cheese to a baking dish. In a small bowl, mix the breadcrumbs with the melted butter and sprinkle over the top of the mac and cheese. Bake in the preheated oven for about 20 minutes until the topping is golden and crispy.
8. Serve the Mac & Cheese hot and enjoy!