Bring a pot of water to a boil.
Generously salt the water, then add the pasta.
Cook the pasta according to the packaging instructions (about 7 minutes). The pasta should be al dente.
Drain and set aside.
Heat a 10 or 12-inch cast iron skillet over medium heat on a stovetop. Melt the butter.
Once the butter is melted, whisk in the flour to create a roux. Continue to whisk until you no longer see or smell raw flour.
Slowly pour in the half and half and heavy cream while you whisk until you have a smooth base for the cheese sauce. There shouldn’t be lumps of roux.
Add the onion powder, garlic powder, salt, and black pepper. Stir.
Remove from the heat, then gradually add 2 cups of grated gouda and 2 cups of cheddar cheese as you whisk. Stop once the cheese is melted.
Preheat your Z-Grill (preferably with branded wood pellets) or other wood pellet grill to 225 degrees Fahrenheit.
Add the pasta to the cheese sauce and stir until the cheese sauce evenly coats the pasta.
Top the macaroni and cheese with the remaining cup of grated gouda.
Transfer the skillet to the grill grates, close the lid, and smoke for 1 hour.
Remove from the grill, let sit for 5 minutes, then serve. Garnish with parsley if desired.