Method
1 Line 2 x 12-hole muffin pans (1/3-cup capacity) with paper patty cases.
2 Beat butter and sugar in small bowl with electric mixer until light and fluffy. Beat in eggs, one at a time, until combined. Transfer to a large bowl; stir in banana. Stir in combined sifted flour and soda and yoghurt, in 2 batches.
3 Divide mixture among paper patty cases.
4 Cook in a moderate oven (180C) for about 20 minutes or until cooked when tested. Stand in pans for 5 minutes before turning onto a wire rack to cool.
5 To make Icing, beat margarine in a small bowl with an electric mixer until light and fluffy. Beat in sifted icing sugar and enough milk to form a spreading consistency. Tint pale yellow with food colouring.
6 Spread icing over cakes; sprinkle with hundreds and thousands.