MAKE IT
Step 1
Preheat oven to 350° F.
Step 2
Prepare pasta according to package directions. Return to saucepan. Add butter; stir until melted.
Step 3
Whisk together evaporated milk, eggs, mustard and pepper in medium bowl. Add to pasta mixture; stir. Add cheddar cheese and American cheese; stir. Cook over low heat, stirring constantly, until cheese begins to melt. Pour into 1 1/2-quart casserole dish.
Step 4
Bake for 10 minutes; stir. Bake for an additional 20 to 25 minutes or until bubbly and top is lightly golden. Season with salt.
Step 5
For Freeze Ahead: Prepare as above; do not bake. Cover; freeze up to 2 months. Thaw overnight in refrigerator. Preheat oven to 350° F. Bake, uncovered, stirring halfway through, for 45 to 50 minutes or until bubbly and top is lightly golden. Season with salt.