Creamy Polenta with Roasted Mushrooms

For the Roasted Mushrooms:

• 1 lb. baby bella mushrooms stems removed and cut in half
• 2 tablespoons olive oil
• 1 tablespoon balsamic vinegar
• 1 tablespoon minced garlic 
• salt and black pepper to taste
• 1/4 cup chopped flat leaf Italian parsley

For the Creamy Polenta:

• 2 cups milk
• 1 1/2 cups water
• 1/2 teaspoon kosher salt
• 3/4 cup stoneground polenta not instant
• 2 tablespoons butter
• 3/4 cup freshly grated Parmesan cheese
• extra parmesan cheese for serving optional