Boil pasta: Cook the pasta in a large pot of salted boiling water according to the package directions until al dente. Drain well and set aside.

Make roux: In a large skillet, melt the butter over medium heat. Sprinkle in the flour and cook, stirring constantly, for about 2 minutes to create a roux.

Add milk and spices: Gradually whisk in the milk to avoid lumps. Stir in the salt, black pepper, dry mustard, and cayenne pepper. Continue to simmer, stirring frequently, until the mixture thickens slightly. Remember not to let it boil.

Melt cheese: Reduce the heat to low and add the shredded cheddar and Pepper Jack cheeses. Stir until the cheeses are completely melted and the sauce is smooth.

Combine pasta and cheese sauce: Add the cooked pasta to the cheese sauce, stirring to coat the pasta evenly. Cook for an additional minute to ensure everything is heated through.

Serve hot: Transfer the spicy mac and cheese to serving dishes. If desired, drizzle with hot sauce for an extra kick. Serve immediately and enjoy the comforting warmth with a spicy twist!