To make the mac and cheese: Preheat the grill to 350°F and grease a 10.25” cast iron skillet with cooking spray. Set aside.
Fill a large pot with water and 1 tablespoon of salt. Bring to a boil over high heat, then add the pasta and cook for about 7 minutes, until al-dente. Strain the pasta and set aside.
To the empty large pot, add the butter, cream cheese, cheddar cheese, gouda, half and half, salt, pepper, smoked paprika, garlic powder, and liquid smoke (if using). Turn the heat to medium-low and cook for about 5-8 minutes, stirring frequently, until all the cheese is melted, bubbly, and slightly thickened.
Turn off the heat, and mix the pasta into the creamy cheese sauce. Taste and add more salt if desired.
Transfer to the prepared skillet and spread into an even layer.
To make the breadcrumb topping: Mix the melted butter, breadcrumbs, salt and pepper together in a medium bowl. Sprinkle over the top of the mac and cheese.
Place the cast iron skillet on the grill and bake using indirect heat for 30 minutes or until the bread crumbs are golden and the cheese is bubbly.
Allow to cool for 5-10 minutes, then serve and enjoy!