Mix rosemary, thyme, salt and pepper and sprinkle over ribs. (Can be left overnight.) Preheat oven to 375 degrees. In batches, brown ribs on all sides adding more oil if necessary. Pour off drippings and discard, add wine to same pot and bring to a simmer, scraping up any brown bits. Return ribs to pot and bring to a boil. Cover; transfer to oven and braise until meat is tender, about two hours. Remove ribs and reduce liquid to 1 ½ cups. Mix butter and flour and whisk into reduced liquid over medium heat, about two minutes. Bring chicken stock to boil. Slowly whisk in polenta until desired thickness, add Gorgonzola and cream. Mix herbs, lemon zest and garlic. Divide polenta among plates, top with ribs and sauce. Sprinkle with Gorgonzola.