Cook the elbow macaroni al dente, according to the package instructions. Pour the macaroni into a foil pan or a similar receptacle that can survive your smoker.
In a large sauce pan, melt the butter over medium heat. When melted, add the milk, and bring to a boil. Add the cream cheese, and melt, whisking often, until sauce is creamy.
Remove the sauce from the heat. Immediately stir in the shredded cheeses, and adding salt and pepper to taste. You must move quickly here, as if you take too long, the sauce will become very difficult to work with as it cools.
Pour the cheese sauce over the macaroni and stir to coat evenly. Pour the bread crumbs on top, forming an even layer.
Place the pan, uncovered, into the smoker, and add your desired wood chips. (For this recipe, I used a combination of pecan and whiskey barrel chips.) Smoke for 30-40 minutes, until the top is browned and the cheese is bubbly.