"Panera" mac and cheese

I have a coworker who raves about Panera mac and cheese. I've still never tried it because I'm always swayed by the turkey sandwiches and fuji apple chicken salad, so I can't compare this to theirs, but it's awesome. I should be embarrassed to say how much of this we ate in one sitting, but it was goooooood. The only thing I changed was using yellow cheddar because the white cheddar wasn't in the grocery store I was in. I've seen it in a different store, but wasn't making two trips that day. It was amazing and the best homemade stovetop mac and cheese I have had. 

Panera Bread’s Signature Macaroni & Cheese

1 (16-ounce) package of rigati pasta (or other small pasta shells)
¼ cup butter
½ cup all-purpose flour
2½ cups 2% reduced fat milk (or cream) --I used skim milk
6 slices white American cheese, chopped  (this is basically white Velveeta...processed cheese)
1 cup (8 ounces) shredded extra-sharp white Vermont cheddar (I used yellow cheddar)
1 tablespoon Dijon mustard
1 teaspoon kosher salt
¼ teaspoon hot sauce
Prepare pasta according to package directions.
Melt butter over low heat. Whisk in flour and cook 1 minute, whisking constantly.
Gradually whisk in milk (or cream); cook over medium heat, whisking until mixture thickens and bubbles. Remove from heat.
Add cheeses, mustard, salt, and hot sauce, stirring until cheese melts and sauce is smooth.
Stir in pasta and cook over medium heat for 1 minute (or until thoroughly heated).

Serves 4 to 6

from Panera's website