Add water and salt to large sauce pan and bring to a soft boil.
Slowly whisk in polenta. It's important to go slowly and continually whisk so you don't get lumps.
Turn heat to low and allow polenta to gently simmer while continually whisking.
When polenta starts to thicken, stop whisking and cover sauce pan.
Allow polenta to simmer with a lid on for 30 minutes, stirring every 5-6 minutes.
After 30 minutes, turn off the heat and add butter.
When butter is halfway melted, stir in the parmesan cheese.
Replace the lid on the pot and allow to sit off the heat for 5 minutes
Taste the polenta and adjust seasoning if necessary.