For the ganache:

1. Melt the chocolate in a medium bowl
2. Separately, bring the cream to the boil.
3. Stir the cream into the chocolate; continue to stir until it has fully combined.
4. Leave to cool until solidified, optionally in the fridge.

To make the centres:

1. Use a ½ tsp rounded measuring spoon to scoop out 30 individual balls that are roughly spherical. Place on a tray covered with cling film.
2. Alternatively, use your hands to roll small balls onto the cling film, but this is very messy!
3. Place the tray in the freezer and leave to freeze completely - the balls should not be compressible. This will take a few hours.

For the chocolate outer shell:

1. Melt the chocolate in a bowl, ideally one without too flat a bottom.
2. One at a time, drop the frozen centres into the chocolate and fish out reasonably quickly with a spoon (the ganache will start to melt after a moment). Place back on the freezer tray.
3. You may need to re-freeze the centres part way through if they begin to melt too easily

Finally:

1. Leave at room temperature before eating. (Test one before serving to make sure the centre has fully defrosted!)