Preheat the oven to 325 degrees F. Grease or butter a 9 x 13 or 8 x 8 ovenproof bakingdish.
Cook the macaroni to al dente, according to package instructions. Drain well, set aside. Shred cheeses and set aside.
Melt the butter in a medium saucepan over low heat, whisk in the flour, continue cookingfor 2 minutes stirring constantly. Slowly pour in the milk, continue whisking to prevent the milk from scalding, and mix until smooth and creamy.
Remove from heat, add in the shredded cheeses, salt, pepper, truffle oil, and thenutmeg, mixing until the cheese has melted.
In a large bowl, combine the cooked pasta and cheese sauce, and gently toss to coat. Transfer to a prepared baking dish.
In a medium bowl, combine the panko, minced garlic, chopped parsley and truffle oil, mixwell. Evenly sprinkle the panko topping over the mac and cheese, and if desired, addsome shredded parmesan as well.
Bake in a preheated 325°F oven for about 30 - 35 minutes or until bubbly and topping isstarting to turn golden, serve hot.