Little chocolate hazelnut cakes

Ingredients

• 250 gram butter, softened
• 1 cup (220g) caster sugar
• 6 eggs, separated
• 300 gram dark chocolate (63 per cent cocoa couverture), melted
• 2 cup (220g) ground hazelnuts
• 1 tablespoon frangelico liqueur (or chocolate or coffee liqueur or 1 teaspoon coffee or chocolate essence)
• 1 teaspoon vanilla extract
• chocolates, to decorate
• Chocolate ganache
• 200 gram dark chocolate (63 per cent cocoa couverture), chopped
• 100 gram butter, chopped