1. Prepare the bakeware by greasing it properly. Preheat the oven to 375°F (190°C). 2. In a mixing bowl, combine uncooked pasta with grated cheese and set aside. 3. In a separate pot, melt butter over medium heat and add flour, stirring constantly to make a roux. 4. Gradually whisk in milk, making sure there are no lumps. 5. Stir in mustard, salt, and pepper, and continue to cook until the mixture thickens and bubbles. 6. Mix the cheese sauce with the pasta, ensuring all the pasta is well coated. 7. Pour into the prepared bakeware and spread evenly. 8. Bake in the preheated oven for about 40-45 minutes or until the top is golden and bubbly. 9. Allow to cool for a few minutes before serving.