Bring a large pot of water to a boil. Add the salt and penne pasta. Cook until al dente according to the package directions (usually 8 to 10 minutes). Drain and set aside.

While the pasta is cooking, prepare the cheese sauce. In a large saucepan or Dutch oven, melt the butter over medium heat. Add the minced garlic and sauté until fragrant, about 30 to 60 seconds, being careful not to brown it. Sprinkle the flour over the butter and garlic and whisk continuously for 1 to 2 minutes until smooth and lightly golden.

Gradually add the heavy cream and milk to the saucepan, whisking constantly to prevent lumps. Continue to cook and whisk until the mixture begins to simmer and thicken, about 3 to 5 minutes.

Reduce the heat to low and add the Parmesan, Asiago, Monterey Jack, and white Cheddar cheeses. Stir until the cheeses are completely melted and the sauce is smooth and creamy.

Add the prepared pasta to the cheese sauce and stir until well coated. Taste the sauce and adjust with salt if desired. Cheeses contain varying levels of salt, so adding salt too early may make your sauce too salty.

Transfer the mac and cheese to a serving dish and top with the shredded Cheddar, crispy bacon, and parsley.