1.Preheat oven to 180°C (160°C fan forced). Line 15 holes of two 12-hole (¹/³-cup/80ml) muffin pans with paper cases.
2.Beat butter, sugar, eggs, sifted flours, powders and milk in medium bowl with electric mixer on low speed until ingredients are combined. Increase speed to medium, beat until mixture is changed to a paler colour. Divide mixture into paper cases, smooth surface.
3.Bake cakes about 25 minutes. Stand cakes in pan 10 minutes before turning, top-side up, onto wire rack to cool.
4.Meanwhile, make malted milk frosting. Beat butter and malted milk powder in small bowl with electric mixer until light and fluffy. Beat in sifted icing sugar and cream, in two batches.
5.Spread cakes with frosting, sprinkle with malt balls.