Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13 inch pan.
In a large bowl, mix together margarine and sugar until smooth. Mix in yolks. Stir in flour and baking powder alternately with the milk.
In another bowl, beat egg whites until doubled in volume. Fold beaten whites into the dough. Spread into a greased 9 x 12 inch pan. Slice bananas over the top of the dough. In a small bowl, mix together the 2 tablespoons sugar and the cinnamon; sprinkle over bananas.
Bake at 350 degrees F (175 degrees C) for 30 to 35 minutes, or until a toothpick inserted into the center comes out clean. Allow to cool.