Arrange polenta slices on a baking sheet; bake 5-7 minutes per side or until hot.
In a large skillet, heat butter over low heat. Add onion and cook 15 minutes, stirring occasionally. Add walnuts, cherries, brown sugar, rosemary, salt and pepper and cook for another 8-10 minutes, or until onions are caramelized.
Top each polenta round with a slice of gorgonzola, a bacon slice and 1 tablespoon of the onion mixture. Serve immediately.