Put the pasta, water, and salt in a large skillet and bring to a boil over high heat. Cook, stirring, until almost all of the water is gone and the pasta is tender.
Add the evaporated milk, Cajun spice, sausage, and peppers and bring to a boil. Reduce heat to medium and cook until the mixture thickens, about 5 minutes. Add the cheeses and cook, stirring, until the cheese is melted. Add additional salt and pepper, to taste.