This mac & cheese is flavorful, fun, and easy. Plus if you're like me and always end up with leftovers you'll be happy to know the dish keeps pretty well in the fridge.
Bring a pot of salted water to a boil. Cook pasta for 1 minute less than package directs. Reserve 1 cup of cooking water then drain pasta.
In a large, deep skillet heat olive oil over high heat. Add sausage and cook, stirring, for 2 minutes or until it begins to brown. Add onions and pepper and cook for another 3 minutes. Add the Cajun seasoning and flour and cook, stirring, for 2 minutes longer. Gradually and carefully whisk in the milk. Whisk until sauce is thickened and smooth, about 5 minutes.
Add the cooked pasta and cheese to the skillet, tossing to combine. Add pasta water to thin sauce if necessary. Reduce heat to medium low and cook for 1 minute.