Fast-As-Boxed Macaroni & Cheese

This recipe is from The Moms' Guide to Meal Makeovers and was requested by my friend Anna.  While this book focuses on improving the way families eat, it is a great resource for healthy eating whether you have a family or not.  For more recipes from the authors of this cookbook, visit their website:  Meal Makeover Moms (the link can also be found on my list of food links in the side margin).
Fast-As-Boxed Macaroni & Cheese
8 oz dried small elbow macaroni (about 2 cups)
1 1/2 cups 1% lowfat milk
2 Tbsp all-purpose flour
1 tsp Dijon mustard
1/2 tsp garlic powder
1 1/2 cups preshredded reduced-fat Cheddar cheese
2 Tbsp grated Parmesan cheese
Cook the pasta according to package directions.  Drain and set aside.
Return the saucepan to the stove (do not place over heat just yet).  Add the milk, flour, mustard, and garlic powder and whisk until well blended.
Place over medium-high heat and bring to a simmer, stirring constantly.  Reduce the heat and continue to simmer and stir gently until the mixture thickens slightly, about 2 minutes.
Add the Cheddar cheese and Parmesan cheese and stir until the cheese melts.  Stir in the pasta, heat through, and serve.
Update 1/15/08:  I made this today with a few modifications and it is getting good reviews, so I thought I would pass along the changes.  First, I used my cost-savings method of using reconstituted dry milk instead milk from the fridge.  I used 1 1/2 cups water and 1/2 cup of dry milk.  Next, I opened my fridge to find that I was out of Dijon mustard so I used yellow mustard instead.  Finally, I added 2 slices of 2% Reduced Fat Kraft American Cheese.  I actually think I like this better!  I plan to post a couple of more favorite macaroni and cheese recipes later.