1.Preheat oven to 170°C/340°F. Line 12-hole (1/3-cup/80ml) muffin pan with paper cases.
2.Stir butter, chocolate, sugar and milk in small saucepan over low heat until smooth. Transfer mixture to medium bowl; cool 15 minutes.
3.Whisk sifted flours into chocolate mixture, then whisk in egg. Drop ¼ cups of mixture into paper cases.
4.Bake about 30 minutes. Stand cakes in pan 5 minutes before turning, top-side up, onto wire rack to cool.
5.Make white chocolate ganache. Bring cream to the boil in small saucepan; remove from heat. When bubbles subside, add chocolate; stir until smooth. Cool 15 minutes. Spread cold cakes with ganache.
6.Run vegetable peeler down side of chocolate to make curls; top cakes with chocolate curls.