Notes from the Test Kitchen:
Oh this took mac-n-cheese to a new level! It was wonderfully creamy. Then you would get a bite of the chorizo and the the crunchy topping. This recipe is a little spicy but not enough to overpower the flavors.
Heat oven to 250 degrees F. Trim and discard crust from bread then cut bread into 1/4 inch cubes. Line 10 by 15-inch baking sheet with foil. Place cubes on baking sheet and bake for 10 to 12 minutes or until dry. Remove from oven and put in a medium mixing bowl, set aside.
Place all the shredded cheeses in a gallon plastic storage bag, seal and shake bag to combine.
Heat oven to 375 degrees. Spray a 3-quart baking dish with non-stick cooking spray, set aside.
Heat oil in a 8-inch non-stick skillet on medium heat. Add chopped onions to skillet, sauté for 3 minutes, add chorizo, sauté for 3 minutes. Remove from skillet with a slotted spoon to paper towels.
In a 2-quart sauce pan melt butter, remove 3 tablespoons of the melted butter and sprinkle over bread cubes. Stir flour, 1 1/4 teaspoons salt, pepper and garlic powder into saucepan with melted butter. Gradually stir in milk, bring to a boil, stir constantly. Reduce heat, simmer for 1 minute then remove from heat.
In 4 or 5 quart pot bring 2-quarts of water with 1 1/2 teaspoon salt to a boil. Add pasta, return to a boil cook for 6 minutes, pasta should be slightly under cooked, pour into colander, drain. Return pasta to cooking pot, sprinkle with chili powder, add white sauce and stir to gently to combine. Add cooked onion and chorizo and 3 1/2 cup of the cheese mixture, stir to blend all ingredients, cheese does not have to melt.
Add crushed nacho chips, cilantro, and remainder of the cheese to bread cubes and toss to combine.
Pour pasta into prepared baking dish. Sprinkle bread mixture over top and bake for 30 to 35 minutes or until heated through and bubbly. Remove from oven and allow to stand for 5 minutes before serving.