In a heavy-bottomed saucepan, bring the Water and the Whole Milk to a gentle simmer over medium heat and season with a pinch of Sea Salt.
Slowly whisk the Coarse Yellow Polenta into the simmering liquid in a steady stream to avoid lumps.
Reduce the heat to low and cook, stirring frequently with a wooden spoon or whisk, until the grains are tender and the mixture is thick and creamy—about 30–40 minutes for coarse polenta. If it becomes too thick, stir in a little more warm water or milk to loosen to your desired consistency.
Remove the pan from the heat and stir in the Unsalted Butter and the grated Parmesan Cheese until fully melted and incorporated; taste and adjust seasoning with more salt if needed.
Let the polenta rest for a couple of minutes to settle, then serve hot as a creamy bed for meats or vegetables, or spread into a dish to cool and slice for grilling or baking.
