In a large saucepan over high heat, stir together the milk and water. Bring to a boil and add the salt. Slowly whisk in the grits, then reduce the heat to low and simmer 25 minutes. Whisk every 7 minutes.
Remove from the heat and add the Parmesan-Reggiano, butter and pepper, stirring until blended. Serve warm.
Recipe by The Tennessee Magazine at https://www.tnmagazine.org/parmesan-reggiano/