Creamy Mac n Cheese

I was looking for a healthier version of Mac n Cheese and found this one from Cooking Light. I couldn't find all the required cheeses, so I sort of made it up from what I found/had on hand.



Ingredients:
1/3 cup all-purpose flour
2 2/3 cups 1% low-fat milk
3/4 cup (3 ounces) shredded Mozzarella cheese
1/2 cup (2 ounces) grated fresh Parmesan cheese
1 cup (2 ounces) light shredded extra-sharp cheddar cheese or mexican cheese mix
6 cups cooked shell macaroni (about 3 cups uncooked)
1/4 teaspoon salt
1/4 cup breadcrumbs

Directions:
Preheat oven to 375°.

Place flour in a large saucepan. Gradually add milk, stirring with a whisk until blended. Cook over medium heat 8 minutes or until thick, stirring constantly. Add cheeses; cook 3 minutes or until cheese melts, stirring frequently. Remove from heat; stir in macaroni and salt.

Spoon mixture into a 2-quart casserole coated with cooking spray. Sprinkle breadcrumbs over pasta mixture. Bake at 375° for 30 minutes or until bubbly.