Cook bacon in a nonstick skillet. Remove all but a thin film of fat from skillet. Cut cold polenta into 3-inch squares, then cut 2 1/2-inch circles out of centers with a glass or cookie cutter. Fry squares and circles over medium-high heat until golden on bottom. Flip and crack an egg into each hole. Cover and cook until whites are set but yolks are still runny. Serve with bacon.