In large cast iron skillet, melt ½ cup butter. Stir in flour, dry mustard and black pepper. Cook for about 1-2 minutes until well combined. Gradually add milk and cook until the mixture is smooth and bubbly, about 10 minutes. You'll want to stir constantly.
While making sauce, cook macaroni until al dente and set aside.
Remove sauce from heat and gradually add the cheese, stirring until melted and smooth. Add pasta and mix until everything is coated.
Stir the breadcrumbs with the melted butter and BBQ rub until combined. Top the macaroni with breadcrumb mixture.
Place in the smoker for 1 hour. Serve immediately.
Notes
Cook the macaroni al dente as it finishes cooking in the smoker.
Don’t use pre-shredded cheese. It doesn’t taste as good and also has addition ingredients that you don’t need.
Once the milk is added to the roux, you must stir constantly as it heats up and becomes thick. Otherwise you’ll have burnt milk on the bottom.
While I recommend a 12 inch cast iron skillet, you can also use a 9x13 pan or disposable aluminum pan.
You want to cook this macaroni and cheese low and slow at 225°F or it will become dry.
Use apple, cherry or maple wood for smoking. They all complement the mac and cheese perfectly.