In your large skillet, bring 4 cups of water to a boil over medium-high heat. Once boiling, add the salt and macaroni.
Cook the macaroni according to the package instructions until al dente, usually around 7-8 minutes. Stir occasionally to prevent sticking.
In a separate bowl, mix the evaporated milk and cornstarch until well combined. This will help thicken your cheese sauce.
Once the pasta is cooked, reduce the heat to medium-low. Drain any excess water if necessary, then pour in the evaporated milk mixture. Stir thoroughly to combine.
Gradually add the grated fontina, asiago, and Parmesan cheeses to the skillet, stirring continuously until the cheese is fully melted and the sauce is creamy.
Once the cheese sauce is well incorporated and creamy, remove the skillet from heat. Serve immediately, garnished with fresh parsley if desired.
