Preheat oven to 350 F. Spray a 9-inch round cake pan with cooking spray.
Cut tube of polenta into 8 slices and place flat side down in cake pan. Dot top of polenta slices with half the butter. Sprinkle with cinnamon to taste.
Bake for 15 minutes or until bottom of slices are lightly browned, then flip. Put remainder of butter on slices and sprinkle on more cinnamon. Bake another 10 minutes. Turn off oven and preheat broiler.
Remove pan from oven. Distribute peach slices (drained, if using frozen) on polenta slices. Sprinkle with brown sugar. Place pan under broiler and cook until sugar and peaches are hot and slightly caramelized.
Serve warm, with ice cream or frozen yogurt, if desired. Serves 4 to 8 people.