Preheat oven at 375. Prepare a 8 1/2 springform pan with cooking spray and flour. To prepare batter, in a mixing bowl, combine margarine, bananas, egg white, lemon peel, vanilla, and milk. In another mixing bowl, combine flour, sugar, salt, and baking powder. Mix wet ingredients with dry ingredients just until moistened. Pour batter into prepared pan. Meanwhile, to prepare topping, combine brown sugar, flour, and cinnamon. Sprinkle topping over batter. Bake for 45 to 50 minutes.