In a slow cooker, combine the tomatoes, tomato paste, mushrooms, onions, bell pepper, capers, brown sugar, chicken bouillon, wine, oregano, basil and garlic. Adjust the seasoning with salt and pepper. Add the chicken, cover and cook on low for 8 hours according to the manufacturer's instructions. The chicken will shred apart. Add the butter until melted and serve over cheesy polenta (recipe below).  

In a large saucepan, combine the stock and half-and-half and bring to a boil. Reduce the heat and, while whisking constantly, slowly sprinkle the cornmeal into the boiling liquid. Simmer, stirring almost constantly with a wooden spoon, until the polenta is thick and smooth, 6 to 8 minutes. Remove from the heat and stir in the mascarpone, Parmesan, salt and pepper.