Steps
1. Preheat oven to 350°F (180°C).
2. In a saucepan, melt butter over medium heat. Stir in flour to make a roux.
3. Gradually whisk in milk until smooth and thickened.
4. Add cheddar cheese and Parmesan cheese, stirring until melted.
5. Season with salt and pepper.
6. In a baking dish, combine cooked pasta, tuna, and cheese sauce.
7. Mix well to coat the pasta.
8. Top with breadcrumbs if desired.
9. Bake for 20-25 minutes until bubbly and golden.
10. Serve hot and enjoy!