Brush 8 ramekins with melted butter, making upward strokes. Place the ramekins on a baking tray in the freezer for 10 minutes. Brush them once more with melted butter, then put them back in the freezer for 10 minutes. Take them out and dust the insides with cocoa powder, making sure to tap out any excess.
Preheat the oven to 200°C/gas mark 6. Melt the chocolate in a bowl over a pan of simmering water, being careful not to allow the bowl to touch the water. Roughly chop the butter and add to the chocolate, stirring until it melts.
Whisk the sugar and eggs until they are light and fluffy and doubled in size. This will take about 5 minutes in a stand mixer, or 5–10 minutes with a handheld mixer. Add the butter and chocolate mixture and mix everything together. Now add the flour and star anise and fold in using a large metal spoon.
Put the ramekins on a baking tray. Divide the mixture between the ramekins, leaving a 1cm gap at the top of each. Cook for 10–12 minutes. The fondants will start to come away from the sides of the ramekins.
Take the fondants out of the oven, and leave in the ramekins for 1 minute. They will still be hot, but they need to be turned out straight away and served, otherwise the residual heat will cook them right through.