To make the polenta, heat the milk and water in a large pot and bring to a boil. While it is simmering, slowly add the polenta. Stir constantly for 6 to 7 minutes, or until the liquid has been absorbed.
Remove from the heat and stir in the mascarpone. Set the polenta aside.
Remove any tuff stem pieces or blemish marks from any of the mushrooms. Cut into quarters. Float in a bowl of cold water to remove any dirt, sand or any inedible particles from mushrooms. Remove from water and air dry on paper towels.
Note: If using Shitake mushrooms, remove stems completely and disregard being that they are inedible. Black gills on the underside of Portobello mushrooms can be removed by scraping with a spoon. For Oyster mushrooms, discard bottom part of stem end and proceed with recipe.
In a large 10-inch sauté pan, heat olive oil to lightly smoking, add mushrooms to sauté pan in 2 batches. Sauté until mushrooms are lightly brown and tender. Remove from heat and place in bowl. While sauté pan is still hot, add an additional » cup olive oil, heat and sauté sliced garlic until lightly brown. Remove from heat and add chopped rosemary. Pour over mushrooms. Season with salt and pepper.
In the same pot that polenta is held in, heat on low setting, no higher or polenta will scorch and burn. Lightly butter 6 5-inch gratin dishes and set aside.
Stirring polenta constantly, add together mozzarella and fontina cheese and wild mushroom ragu. Now you’re ready to serve.
Spoon equal amounts of creamy polenta into each gratin dish but do not overfill. Sprinkle with parmesan cheese, place on upper shelf of broiler and broil until cheese is lightly brown and polenta is crusty. This step will only take a minute or two, do not walk away from broiler!
When lightly brown, sprinkle with fresh chopped parsley and serve immediately on underliner.
Preheat broiler to highest setting before beginning this step.