Preheat oven to 350 degrees F. In a large pot, bring 1 gallon of water to boil. Add 2 teaspoons salt and pasta and cook for 8 - 9 minutes
Drain pasta and cool under cold running water. Pasta should be slightly firm. Toss drained pasta in oil and reserve
Melt butter in a large sauce pot over medium heat. Add onions and saute for 4 - 5 minutes.
Add flour and cook 1 - 2 minute but do not brown.
Add cream, half and half, kosher salt and white pepper.
Bring pot to a simmer. Cook until sauce is thick, about 5 - 6 minutes Blend cheese into sauce and add cooked pasta.
Pour pasta and sauce into a 9 x 12" baking dish. Reserve.
In a saute pan over medium-high heat, add oil and chipotle chili powder. Heat for 30 seconds, until pan starts to smoke. Remove from stove and stir in bread crumbs. Sprinkle bread crumbs over macaroni and cheese and bake for 20 minutes.