- Spray a deep-sided tray with oil, line with parchment paper and sieve over icing sugar.
- In a thick-bottomed saucepan, heat the sugar and water until it reaches 135C on a sugar thermometer.
- Three minutes before the sugar stage, whisk your egg whites in an electric mixer, pour in the passionfruit syrup and drained basil seeds, then add the sugar syrup in a steady stream and beat on medium speed until cool - about 15 minutes.
- Pour into the tray and allow to set overnight. Cut with a warm knife or wet cookie cutter, placing the tubes of marshmallow on to disposable chopsticks for toasting.
- Coat in icing sugar.