For the mac and cheese, bring a pot of salted water to a boil then add the pasta and cook until al dente, about eight minutes. Drain the pasta and leave it in the colander until ready to use.
Meanwhile, melt the butter in a medium saucepan over medium heat. Add in the garlic and cook for about one minute then sprinkle in the flour. Whisk the flour in and cook, whisking constantly, for about one to two minutes to toast the roux. While continuing to whisk, slowly pour in the warm milk, salt, and dry mustard powder and bring it all to a light simmer. Cook, whisking frequently, until thick, about four to five minutes.
When the sauce is thick, turn the heat down to low and whisk in the cream cheese, orange cheddar, and parmesan cheese. Switch to a heatproof spatula or a wooden spoon and carefully stir in the cooked macaroni making sure that every noodle is well coated. Remove from the heat and cover with a lid to keep warm.
Pour one tablespoon of butter into a cast iron skillet and place it over medium heat. Meanwhile, in a small bowl stir together the remaining two tablespoons of butter, chopped garlic, Italian seasoning, and one tablespoon of parsley. Stretch the pizza dough into a round that will fit inside your cast iron skillet, using a little flour if the dough is sticky. Carefully place the dough into the hot cast irons skillet then pour the garlic butter over the dough, using a spoon or pastry brush to evenly distribute the butter, garlic, and herbs. Spoon the mac and cheese onto the dough being sure to leave about a one-to-two-centimeter crust around the edge. Scatter the top of the pizza with grated cheddar cheese and pop it into the oven to cook for 20 minutes or until the crust is golden brown.
Remove the pizza from the oven and allow it to cool slightly before scattering with parsley, slicing, and serving.