Directions

1. Preheat oven to 350°. Bring a large pot of salted water to a rolling bowl, add pasta, and cook according to directions until al dente (it will continue to cook when it bakes). Scoop out about ½ cup hot pasta water and set aside. Drain pasta and rinse with cold water. Transfer pasta to a large bowl.
2. Meanwhile, melt butter in a medium saucepan over medium heat. Whisk in flour, slowly adding a little bit at a time, and cook until a light brown color is achieved. This is your roux. Whisk in milk a little at a time until smooth.
3. Reduce heat to medium-low and slowly start adding about three-quarters of the cheddar cheese. Continue whisking until cheese is completely melted. Slowly add three-quarters of the Colby jack and whisk until melted. Remove cheese sauce from heat and stir in Cajun seasoning.