Shred the cheeses, combine them, and set aside. Preheat the oven to 375 F, and butter a 9x13-inch casserole dish.
Cook and drain the elbow macaroni until al dente, add the butter, and stir until melted. Set aside.
Whisk together the eggs, and evaporated milk. Garlic powder, onion powder, mustard powder, paprika, salt, and pepper.
Assemble the casserole: - Place ⅓ macaroni in the bottom of the baking dish- Sprinkle ⅓ of cheese on top- Repeat with the rest of the pasta and cheese- Pour the egg mixture evenly over the pasta and cheese.- Bake for 45 minutes, and let stand for 10 minutes before serving