In a medium saucepan, melt 2 tablespoons butter over medium heat. Add 1 cup cream, milk and salt. Bring to a low simmer. Gradually whisk in cornmeal. Cook and stir for 3 minutes. , Pour polenta into a 3-quart slow cooker coated with cooking spray. Cook, covered, on low for 2 hours, stirring every 30 minutes. Meanwhile, in a small saucepan, bring vinegar and sugar to a boil. Reduce heat; simmer, uncovered, until reduced to 1/3 cup. Just before serving, stir cheese and the remaining cream and butter into polenta. To serve, drizzle with balsamic glaze.