Sprinkle the remaining 1 cup Monterey Jack and 1 cup pepper jack over the top. Repeat the layers, ending with the corn mixture. Layer with half of the macaroni mixture, then half the corn mixture.
In a separate pan, cook the onions in the butter over a low heat until caramelized, 20 to 30 minutes, stirring occasionally.Remove from the pan and cut into bite-size pieces. Fry the bacon in a skillet over medium-high heat until slightly crisp, about 8 minutes.Serve immediately (while it's still very creamy) or pour into a buttered baking dish, top with extra cheese and bake until bubbly and golden on top, 20 to 25 minutes. Pour in the drained, cooked macaroni and stir to combine.Taste the sauce and add more salt and seasoned salt as needed! DO NOT UNDERSALT. Add 1/2 teaspoon salt, 1/2 teaspoon seasoned salt and the pepper. Pour the egg into the sauce, whisking constantly. Take 1/4 cup of the sauce and slowly pour it into the beaten egg, whisking constantly to avoid cooking the eggs.Pour in the milk, add the mustard and whisk until smooth. Cook for a couple of minutes, whisking constantly. In a large pot, melt the butter and sprinkle in the flour. Cook the macaroni until still slightly firm.Top each serving with some sour cream and salsa if desired.Taste and adjust the seasoning, thinning with a splash of milk if needed. Pour in the cooked pasta, add the taco meat and stir to combine.
Add the processed cheese and cook, stirring, until melted. In the same pan over medium heat, add the remaining 2 tablespoons butter and the milk and cook until hot and bubbling.
Cook until the sauce thickens, 2 to 3 minutes, then remove to a bowl (it will still be a little juicy). Stir in the diced tomatoes and chiles, hot water, 1 teaspoon salt and 1/2 teaspoon pepper and bring to a simmer. Stir in the chili powder, cumin, onion powder, garlic powder and paprika. Add the ground beef and cook, crumbling it with a wooden spoon, until browned, 5 to 8 minutes.