Place about ¾ of white chocolate into a heatproof glass bowl. Place over a pan of hot water ensuring the water doesn't touch the base of the bowl.
Heat gently, stirring the chocolate making a note of the temperature. Melt the white chocolate to 43℃ / 110℉. Be careful not to take it any higher than this temperature as it could soon seize and become unworkable!
Cool the chocolate. Remove the bowl from the pan and wipe the base dry. Stir in the remaining chocolate watching the temperature. You're aiming for it to reduce to 25℃ / 78℉. This will take a number of minutes and will start to thicken as it cools.
Reheat the chocolate to make it workable. Return the bowl of chocolate to the pan of hot water and continue to stir and monitor the temperature so that you reheat the chocolate to 28℃ / 82℉. The chocolate is now tempered.
Remove the bowl from the heat again and wipe the base dry.
Fill the chocolate mould. Use a ladle or large spoon which is completely dry to pour chocolate into the chocolate mould. Once completely full tap the chocolate mould on the work surface a few times to remove any air pockets in the chocolate.
Then tip the mould upside down over the bowl of melted chocolate to remove the excess chocolate.
Give it a shake allowing the excess to drip out. Return the mould the right way round and place on the work surface. Run a knife over the top of the mould to remove excess chocolate. This will neaten the edges of the chocolates and make it easier to remove them from the mould later.
Check that all of the surfaces have been completely covered in chocolate. Pour more chocolate into the mould and empty it out as before if necessary. Set the chocolate mould aside in a cool until set, avoid putting it in the fridge.