Preheat oven to 350℉. Using 1 tablespoon olive oil, brush both sides of the polenta rounds and place them in a baking dish or on a cookie sheet. Cook for 20 minutes in the preheated oven.
In a large pan, heat the remaining 2 tablespoons olive oil over medium heat. Add the garlic and sauté for 1 minute. Then add the mushrooms. Sauté for 6-8 minutes, or until the mushrooms are tender. Stir occasionally.
Add the black beans, beer and goat cheese to the mushrooms. Stir well and increase heat to medium high. Cook for an additional 10 minutes. Add the minced parsley, stir and remove from heat.
Remove polenta from the oven. Place 3 polenta rounds on a plate, and spoon the mushroom/black bean mixture over the polenta. Serves 4.