Cook cavatappi in boiling water for 1 minute less than the package directs, about 8 to 10 minutes. Drain well.
Whisk cornstarch into 1/2 cup of the cooking milk until smooth. Heat the remaining 2 cups cooking milk and evaporated milk in a large saucepan over medium heat until steaming.
Whisk in the cornstarch mixture and simmer for 1 to 2 minutes until lightly thickened. Reduce heat to low and stir in cream cheese until smooth.
Remove from heat and stir in cheddar, mustard, salt, black pepper and cayenne until the cheese melts. Fold in pasta, leaving it generously coated with sauce.
Freeze after cooking: divide among 6 shallow freezer containers, refrigerate within 2 hours and chill fully. Seal, label and freeze for up to 2 months.
Thaw overnight in the refrigerator. Reheat in a covered saucepan over low heat with a share of the reserved milk, stirring gently for 8 to 12 minutes until the pasta reaches 165°F.
Serve one-sixth of the batch per portion, adding the milk gradually so the sauce stays creamy rather than soupy.