Preheat the oven to 400 degrees F. Grease a nonstick 10-15 cup bundt pan with butter or nonstick cooking spray. Mix 1/4 cup breadcrumbs and 1/2 cup parmesan cheese together. Pour it in the bundt pan and shake the pan around until all sides are coated with the mixture.
Place a large pot of water over high heat and bring to a boil. When the water starts boiling, stir in the pasta and boil until almost cooked through, but still firm. About 5 minutes.
Meanwhile, place the butter in another pot over medium heat. Once the butter starts melting, whisk in the flour. Then whisk fast while pouring in the milk to break up the flour clumps. Break the eggs into a bowl and beat. Then whisk fast again to incorporate the eggs into the milk mixture without scrambling them.
Stir in the Old El Paso Taco Seasoning and green chiles. Then add the cheese and stir until melted into the mixture. Once the pasta is nearly cooked, drain the pasta and add it to the cheese sauce. Add the remaining 3/4 cup breadcrumbs and stir to thoroughly coat the pasta.
Pour/scoop the mac and cheese into the prepared bundt pan. Bake for 30-40 minutes until crisp around the edges and bubbly. Cool for 15 minutes in the pan. Then run a long thin spatula around the edges and down the sides. Flip the bundt out onto a serving platter. Serve warm or at room temperature.
NOTE: It's very important to use a nonstick pan and grease it well. You don't want your mac and cheese loaf to break when you flip it out of the pan!