Ragout:

1. Heat a large skillet over high heat.
2. Add the mushrooms and cook, stirring frequently until juices have evaporated and mushrooms brown a bit.
3. Lower heat to medium and add the shallot, rosemary, salt and pepper. Saute another 2 minutes.
4. Stir in the stock, wine and tomato paste. Cook 10 minutes or until the liquids reduce to a gravy consistency.
5. Cover and keep warm.

Polenta:

1. Bring stock, milk, salt and pepper to a strong boil in a deep saucepot. Whisking constantly, slowly drizzle the polenta in.
2. Turn heat down to medium and whisk constantly.
3. Slowly turn the heat down to low as the polenta thickens. Whisk less frequently, making sure to get into the corners of the pot. Total cooking time will be ~15 minutes.
4. Remove polenta from the heat. Stir in cream and parmesan.
5. Spoon polenta into a serving bowl and ladle the ragout into the center.
6. Top with a dollop of mascarpone and some grated parmesan.