Parmesan Polenta

0 Bring the stock to a boil in a saucepan. Keep warm over a medium flame.
1 In a medium saucepan, bring the milk and half-and-half to a foamy simmer. Reduce the flame to medium and add the polenta to the foaming milk mixture, stirring constantly.
2 When the mixture becomes thick, begin adding the hot stock, ½ cup at a time. Let the stock absorb completely before adding the next ½ cup, stirring all the while.
3 Once all the stock has been added, reduce the heat and add the butter, mascarpone, and Parmesan cheese, stirring well to blend. If the mixture is too thick, add a bit of milk or stock, then season with salt and pepper. 
4 Spoon into a serving dish and serve immediately