1/4 cup all-purpose flour
2-1/2 cups 1% low-fat milk
1 cup (4 ounces) shredded extra-sharp cheddar cheese, divided
6 ounces light processed cheese, cubed (such as Velveeta Light)
6 cups hot cooked elbow macaroni (about 3 cups uncooked)
1/4 teaspoon salt
3/4 cup panko
Preheat oven to 375°.
Lightly spoon flour into a dry measuring cup, and level with a knife. Heat a large saucepan over medium heat; add flour. Gradually add milk, stirring with a whisk until blended. Cook until thick (about 8 minutes), stirring frequently. Stir in the cheddar cheese and processed cheese; cook 3 minutes or until cheese melts, stirring frequently. Remove from heat; stir in macaroni and salt.
Spoon the mixture into a 2-quart casserole dish coated with cooking spray. Sprinkle with the panko. Bake at 375° for 25 minutes or until bubbly.