Bring milk and water to boiling in large saucepan over high heat. Add salt, garlic powder, onion powder and black pepper.
Gradually stir in polenta; cook, stirring the mixture constantly, for 3 to 5 minutes or until polenta thickens and pulls away from sides of saucepan. Stir in Parmesan and butter. Remove from heat. Makes 7-1/4 cups.