Combine the milk, broth, and salt in a large saucepan over medium-high heat. Once the liquid has just started to boil, gradually add the polenta while whisking constantly.
Reduce the heat to simmer and continue to whisk every few minutes, for 25 minutes. Add the butter and Parmesan cheese and season with sea salt and freshly cracked pepper, to taste. Stir until well combined.
Pour into a serving bowl and top with more shredded Parmesan and freshly cracked black pepper. Serve and enjoy.