Preheat the oven to 375.

1. Butter a 9 inch deep dish pie plate.
2. Sprinkle the bottom and the sides with the bread crumbs.
3. Fill a large pot half full with water, add ½ teaspoon of the salt and the oil.
4. Bring it to a boil over high heat.
5. Stir in the macaroni.
6. Cook without covering the pot for about 5 minutes or just until the macaroni is almost tender.
7. Drain macaroni, rinse with cold water, and drain well (you need 5 cups).
8. Melt the butter in a large skillet over medium high heat. Add the onion and sauté until soft, about 5 minutes.
9. Stir in the flour, the remaining teaspoon of salt, the mustard, pepper and nutmeg, then cook until bubbly, about 1 minute.
10. Gradually stir in all of the milk. Continue to cook and stir until the sauce simmers and thickens.
11. Add 2 cups of cheese, plus the red and yellow food colorings (if you wish). Stir until completely melted and blended (the color of the sauce should be light golden).
12. Remove the sauce from the heat.
13. Fold in the macaroni.
14. Spoon the macaroni into the pie plate, piling it high in the center.
15. Top with the remaining ½ cup of cheese. Sprinkle generously with the paprika.
16. Bake the pie until golden brown and bubbly, about 25 minutes.
17. Let the pie stand on a wire rack until set, about 15 minutes, then slice it into wedges. Store any leftovers in the refrigerator.