Preheat oven to 180°C and grease a 12-hole muffin tin with butter.
Melt 150g dark chocolate over a pan of simmering water and let cool.
Cream 150g butter with caster and brown sugars until light.
Gradually beat in the eggs.
Stir in sieved flour, baking powder, and cocoa, then fold in melted chocolate and cherries.
Mix in buttermilk and 5 tablespoons of syrup, then fill muffin holes three-quarters full.
Bake for 15-20 minutes until a skewer comes out clean.
Boil cherry syrup, sugar, and cherry brandy in a pan until sugar dissolves.
Syringe the syrup into warm cakes and allow them to cool.
Core the cooled cakes and pipe whipped cream into the center before refrigerating.
Warm 100g double cream to a simmer for the ganache.
Whisk in 200g of broken chocolate pieces until shiny and allow to firm slightly.
Spread ganache over the cakes and let it set.
Roll cakes in nonpareils and return to the fridge.
Mould fondant into hearts and strips for final decoration.
Wrap fondant strips around the base of each cake using a little water to stick.
Secure a gold heart on top of each cake with a dab of ganache.