Comine the macoroni, 4 cups water and 1 TBS salt in an
Instant Pot. Seal instant pot. Set to pressure cook on high
for 4 min. After pressure cook cycle is complete, do quick
release and wait until the quick release cycle is complete.
Unlock, remove lid and switch to low saute setting. Stir in
the evaporated milk, butter and 1/4 cup water. Add cheddar,
a little at a time, while constantly stirring, until the cheese is
completely melted. Serve hot.