Boil the water and cook the macaroni for about 7 minutes. It will still have a pretty firm bite as it will continue to cook as you finish the recipe.
Drain the pasta and run some cool water over it to stop the cooking and to help keep it from sticking together. Return the pot to the stove and add the butter. Add the flour when the butter has melted
Cook the roux for a few minutes over medium heat being careful not to darken the roux.
Add the milk while whisking and bring to a boil then reduce to simmer for about 5 minutes to cook out the flour.
Add the remaining ingredients except for the potato chips and mix well. If all the cheese has not melted yet it will during the baking process. Fold in the pasta.
Top with potato chips and bake at 375 til bubbly. About 20 minutes.