Step 1

Preheat oven to 350˚F.

Step 2

Cook pasta for 3 minutes and drain well.

Step 3

In medium saucepan, melt butter. Stir in flour, mustard, salt, and pepper.

Step 4

Gradually add milk and cook until mixture is smooth and bubbly, stirring constantly.

Step 5

Cook over medium heat until mixture boils, stirring constantly.

Step 6

Turn heat to low and simmer 1 minute, stirring constantly.

Step 7

Gradually mix in cheese and stir until cheese is melted.

Step 8

Add pasta; mix lightly. Pour into 2-quart casserole.

Step 9

Top with croutons. Bake uncovered for 25 minutes or until internal temperature reaches 165-175 degrees.