I have never had a problem with the consistency of this recipe. Although it is important to note that not all slow cookers run at the same temperature. Only cook this recipe on LOW.
If you have a tendency to have problems with pasta or cheese sticking in your slow cooker, you can mix the ingredients together in a large bowl instead of the slow cooker. After greasing the slow cooker well, place a 1/2 cup of broth or 4 tablespoons of butter on the bottom of the slow cooker. Then, add the macaroni mixture.
Additionally, this recipe is thick and creamy. If you would like it a little thinner, just add small amounts of broth at the end of cooking until desired consistency is achieved. Enjoy!