Boil the cavatappi in water with 1 teaspoon salt for 3 minutes less than the package directs and drain.
Melt the butter, whisk in the flour for 1 minute, and gradually whisk in the warm milk and evaporated milk until lightly thickened.
Place the pasta, sauce, pepper and remaining salt in a buttered 6-quart crockpot and cook on low for 45 minutes.
Stir in the cheddar and fontina by handfuls, followed by the mozzarella and Parmesan.
Cover and cook on low for 30 to 45 minutes until the sauce is smooth and the pasta is tender.