Bring the stock and milk to the boil in a pan. Stir in the polenta, reduce the heat, simmer for approx. 2 mins., stirring constantly to form a thick paste, spread the polenta approx. 1.5 cm thick onto the back of a baking tray that has been rinsed in cold water, leave to cool. Cut out 12 circles (each approx. 6 cm).
Mash the polenta cut-offs with a fork, mix with the carrot and parsley, season with salt. Transfer the mixture to the prepared dish. Arrange the polenta rounds, tomatoes, meat and cheese on top so that they overlap a little, then season.
Approx. 25 mins. in the centre of an oven preheated to 220°C. Remove from the oven and sprinkle with parsley.