To prepare stew: Place flour, garlic powder, thyme, basil, ½ teaspoon salt, and pepper in a plastic bag. Add meat pieces, a few at a time, shaking to coat. In a Dutch oven brown meat, half at a time, in hot oil; drain fat. Return all meat to Dutch oven; add chopped onion, dried rosemary (if using), and garlic. Cook and stir until onion is tender. Stir in broth and wine. Bring to boiling; reduce heat. Simmer, covered, for 1- ½ hours.
Stir in boiling onions and carrots. Bring to boiling; reduce heat. Simmer, covered, about 30 minutes more or until meat and vegetables are tender.
Meanwhile, prepare polenta: In a large saucepan, bring milk just to simmering over medium heat. In a medium bowl, stir together cornmeal, water and salt. Slowly add the cornmeal mixture to the simmering milk, stirring constantly. Cook and stir until the mixture comes to a boil. Reduce heat to low. Cook for 10 to 15 minutes or until the mixture is very thick, stirring occasionally. (If the mixture is too thick, stir in additional milk.) Stir in butter until melted.
Just before serving, stir parsley, tomato paste, and the 1 teaspoon fresh rosemary, if using, into stew. Serve the stew over the polenta. If desired, garnish with rosemary sprigs.