Bring large pot of salted water to a rolling boil. Cook pasta according to package instructions to al dente. Drain, rinse briefly to prevent sticking and set aside.
In large skillet, cook andouille sausage over medium heat, stirring periodically until brown and crispy, approximately 5 minutes. If sausage begins sticking to pan at any point, add 1-2 teaspoons olive oil.
In large saucepan or Dutch oven, melt butter over medium low heat. Add flour, whisking to combine. Continue whisking for approximately 5 minutes. Slowly whisk in milk, add salt and turn up heat to bring mixture to boil, whisking constantly. Mixture will begin to thicken. Continue whisking until sauce is thickened and coats back of spoon. Remove from heat and immediately stir in cheese, a handful at a time, while sauce is still hot. Stir in elbow pasta, coating evenly with sauce. Season with additional salt if desired.
Before serving, top each bowl of macaroni and cheese with generous helping of andouille sausage and fresh ground black pepper.