Preheat the oven to 400°F (200°C). Bring a large pot of salted water to a boil. Cook the pasta according to package directions until al dente. Drain well.

Meanwhile, in a large bowl, whisk together the milk, beaten eggs, sour cream, and cajun seasoning (or 1/2 teaspoon salt and 1 teaspoon pepper).

Add the cooked pasta, salted butter, shredded cheddar cheese, and 2 cups of the shredded Colby Jack cheese to the milk mixture. Mix everything until well combined.

Pour the pasta mixture into a 9x13 inch baking dish and cover tightly with aluminum foil.

Bake for 25 minutes. Remove the foil and sprinkle the remaining 1 cup of Colby Jack cheese over the top. Return to the oven and bake for another 10 minutes, until the cheese is melted and bubbly. Switch the oven to broil and broil for 2-3 minutes, watching closely, until the top is golden and slightly crispy.

Serve the mac and cheese immediately, garnished with fresh basil or parsley and a sprinkle of black pepper. Enjoy!