In a wide, heavy bottom pot combine the polenta, milk, water, rosemary, bay leaf and garlic. Turn the heat to high and while stirring bring the liquid to a boil.
Reduce the heat, season with salt (careful as we add parmesan in the end) and simmer for about 15 minutes until the polenta has thickened and then add some pepper.
Switch off the heat and remove the bay leaf, rosemary sprig and garlic clove. Now add the butter and then parmesan and combine well.
Pour the polenta inside the prepared form with overlapping cling film. Cover THE polenta completely with the overlapping cling film and chill for at least 2 hours in the fridge.
Once the polenta has chilled and feels firm, transfer to a cutting board and cut into a rectangular shape.
To pan fry the polenta, place a pan on medium heat and add olive oil. Sear the polenta cakes for about 5 minutes on one side until brown and crispy.
Flip the cake over and cook the other side the same way. Repeat with the remaining cakes and serve immediately or re-heat in the oven when needed.