Bring a pot of salted water to a boil. Add elbow macaroni and stir every few minutes until cooked al dente. 8-10 minutes.
Drain pasta in a collander running cool water over the pasta until room temperature.
Cube Velveta into 1 inch cubes and add to a pot along with dry rub and milk. Simmer over low heat until the velveta has melted. dont let milk come to a boil. Once cheese has melted turn off heat and stir in 1 cup of cheddar cheese and the elbow macaroni.
Pour macaroni and cheese mixture into a cast iron skillet and top with remaining cheddar cheese. Place skillet in the smoker set at 350 degrees F. for 30-45 minutes until hot but not boiling over. Garnish with chives. (optional)