Cream margarine and sugar. Add egg, beaten until fluffy.
Combine Vanilla with milk and add alternately with dry ingredients to creamed mixture.
Brush a 8 in square pan (I used a round cake pan but it turned out a little thicker then I would have liked) Grease pan. Pour batter in pan and arrange apples slices in overlapping rows on top of batter. Crumble topping on top.