1.Preheat oven to 170°C/340°F. Line 12-hole (⅓-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 cup 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.Tint one-third of the icing pink; leave remaining portion white. Roll each colour, one at a time, between sheets of baking (parchment) paper until 5mm thick. Using cutter, cut 8cm rounds from white icing. Cut 3cm heart shapes from the pink icing and from the centre of the white icing rounds. Remove the white heart shapes and discard; replace them with the pink hearts. Gently re-roll the icing rounds between sheets of baking paper to ensure the hearts are in place.
6.Brush the top of each cake with a little jam; position rounds on cakes.