Preheat the oven to 325℉. Boil the macaroni until al dente (not too soft). Once done, drain the water and put the macaroni to the side. Also, get your cheeses ready by grating them.
1 pound elbow macaroni
In a saucepan, melt butter over medium heat. Then mix in the flour, garlic powder, salt, and pepper. Stir and cook this for about 2 minutes.
4 tablespoons salted butter, 4 tablespoons all-purpose flour, 1 teaspoon salt, ½ teaspoon ground black pepper, ½ teaspoon garlic powder
Next, pour in the milk very slowly, followed by the half and half. Keep stirring the entire time so it mixes well and does not curdle. Let it heat until it just starts to bubble.
3¼ cup whole milk, 2 cups half and half
Take the pot off the heat. Now, add the truffle oil and the shredded cheddar and gruyere cheese. Keep stirring until all the cheese melts into the sauce.
3 cups sharp white cheddar, 2 cups gruyere cheese, 1 tablespoon white truffle oil
Add the truffle cheese sauce to your pot with cooked macaroni and stir so every piece is covered.
Grab a baking dish (about 9x13 inches) and lightly grease it. Pour in half of your cheesy macaroni. Sprinkle half of your parmesan cheese over this layer.
½ cup parmesan cheese
Add the rest of the macaroni on top and sprinkle the remaining parmesan cheese over it.
In a small bowl, mix the breadcrumbs with melted butter and a bit more truffle oil. Scatter this mix evenly on top of your dish. Put it in the oven and bake for about 10-15 minutes, or until you see it bubbling up.
1 cup panko breadcrumbs, 2 tablespoons salted butter, 1 tablespoon white truffle oil
To finish, set your oven to broil on high and let the top get golden-brown and crispy, about 3-5 minutes. Take it out, let it cool a bit, then serve warm and enjoy!