A candy thermometer isn't the only item Patel recommends. She also suggests using "A heatproof bowl, spatula, double boiler ...

Not using a candy thermometer is the first mistake many ... but if you really want to get serious about chocolate, this double boiler is where it’s at. This nifty vessel is essentially two ...

A thermometer is particularly crucial when melting chocolate in a double boiler, since the chocolate cooled a lot more slowly with this method. When you are ready to test the tempered chocolate ...