Mix together the rolled oats, flour, baking powder and cinnamon. Beat in the eggs and the milk (or apple juice). Add the grated apple. Mix well. Spoon one-fourth of the mixture at a time onto a hot, lightly oiled skillet. Using a spatula, spread the batter out to a thickness of about one third of an inch. Cook over medium-high heat until bubbles appear and the surface begins to dry out. Turn over and cook until done.