Penne au Gratin

Directions

1. 1
   Bring 2 1/2 quarts of water to a boil in a pot.
2. 2
   Add the penne, bring the water back to a boil, and boil the pasta over medium heat, uncovered, for about 8 minutes.
3. 3
   (The pasta should be al dente, firm to the bite.)
4. 4
   Drain the penne in a colander and rinse it under cold tap water until cool, and set aside.
5. 5
   Heat the butter and oil in a saucepan, and add the flour.
6. 6
   Cook the mixture over medium heat for about 10 seconds, then add the milk, stir it in quickly with a whisk so the mixture doesn't scorch.
7. 7
   Bring the mixture to a boil, and boil it for 10 seconds.
8. 8
   Add the cheddar cheese, salt and pepper, mix well, then cook over low heat for 3 to 4 minutes.
9. 9
   Set aside.
10. 10
    When ready to finish the gratin, preheat the oven to 400 degrees.
11. 11
    Mix the pasta with the cheddar sauce, and transfer the mixture to a 6-cup gratin dish.
12. 12
    Sprinkle the tomato on top of the pasta and sauce.
13. 13
    Combine the Parmesan and paprika in a small bowl, and sprinkle the mixture on the pasta.
14. 14
    Bake in a 400 degree oven for 30 minutes, until the gratin is bubbly and nicely browned on top.
15. 15
    Serve immediately.
16. 16
    Note: If making the gratin at the last moment, and assembling it while the sauce and pasta are both hot, do not bake the gratin.
17. 17
    Instead, place it under a hot broiler until golden brown on top.