Bring a pot of salted water to a boil and cook the elbow pasta until al dente. Stir periodically during cooking to keep the noodles from sticking together.
Drain the cooked macaroni thoroughly, then set it aside while preparing the sauce.
Using the same pot, melt the unsalted butter over medium heat.
Stir in the all-purpose flour, ground mustard, garlic powder, onion powder, black pepper, cayenne pepper, and salt. Mix thoroughly and cook the seasoned roux for approximately 2 minutes.
Slowly whisk the heavy cream and whole milk into the roux, ensuring the mixture remains smooth.
Continue whisking for about 5 minutes, or until the sauce has noticeably thickened.
Gradually stir in the sharp cheddar, medium cheddar, and Colby Jack, adding the cheese while stirring continuously. Continue until all the cheese has melted and the sauce is smooth and creamy.
Preheat the oven to 375°F (190°C) and grease a baking dish.
Transfer half of the cooked macaroni to the prepared baking dish, then distribute some of the cheese sauce over the pasta.
Add the remaining macaroni and cover it with additional cheese sauce, making sure the pasta is thoroughly coated.
Bake the assembled macaroni and cheese for 15 to 18 minutes, or until the cheese is completely melted and the casserole is hot and bubbling.
Remove the casserole from the oven and allow it to stand for approximately 5 minutes before serving.