Fill a large saucepan three-quarters full with water and bring to a boil over high heat.  Once boiling, add 2 tablespoons of the salt to the water and then the pasta.  Cook the pasta until just al dente, according to the manufacturer’s instructions.  Remove from the water, drain well, and place in a medium bowl.  Add the milk, heavy cream, Fontina, Gruyere, Cheddar, Essence, the remaining 1/2 teaspoon of salt, black pepper and nutmeg and stir well to combine. 

Place the pasta into the deep casserole pan and in a separate, small bowl, combine the bread crumbs, Parmesan cheese and butter and stir to blend.  Sprinkle over the top of the pasta and place in the basket of the Air Fryer, and close the drawer.  Set the temperature to 350 degrees Fahrenheit and the timer for 30 minutes.  When the timer goes off, remove the deep casserole pan and allow the Mac & Cheese to cool for at least 20 minutes before inverting the deep casserole pan over a plate and removing the pan to release the mac & cheese. Cut into wedges and serve warm.