►Heat oven to 400°F. Grease a 9-inch-by-13-inch baking dish.
►Bring a large pot of salted water to a boil and cook macaroni for 2 minutes less than package directions. Drain and transfer cooked pasta to a large mixing bowl. Toss with 2 tablespoons butter until pasta is coated. Set aside.
►Melt remaining 2 tablespoons butter in a large saucepan over medium heat. Add flour and cook, whisking constantly, until a light golden paste forms. Whisk in milk, season with salt and pepper, and cook, whisking, until mixture is very thick and no floury taste remains, 8 to 10 minutes. Reduce heat to low and stir in three-quarters of smoked cheddar until smooth. Stir in hot sauce, ground mustard, and garlic powder. Taste and adjust seasoning with salt and pepper.
►Pour cheese sauce over cooked pasta and stir to combine. Let cool for 10 minutes. Stir in fontina and pulled pork and mix well.
►Pour mixture into prepared baking dish and top with panko and remaining smoked cheddar. Bake until browned and bubbling, about 45 minutes. Drizzle with barbecue sauce and serve.