Mix rosemary, garlic, 2 teaspoons salt and pepper; rub over meat. In a large skillet, heat oil over medium-high heat; brown meat. Transfer meat a 5- or 6-qt. slow cooker. Add broth to skillet; cook 1 minute, stirring to loosen browned bits from pan. Pour over meat. Cook, covered, on low until meat is tender, 7-9 hours., For polenta, in a large heavy saucepan, bring water, milk and remaining 1 teaspoon salt to a boil. Reduce heat to a gentle boil; slowly whisk in cornmeal. Cook and stir with a wooden spoon until polenta is thickened and pulls away cleanly from sides of pan, 15-20 minutes. (Mixture will be very thick). Remove from heat; stir in Parmesan cheese and butter. Serve with roast. If desired, serve with additional rosemary and Parmesan cheese.