Extra time:2hr setting ›
- Line a 20cm square tin with baking parchment and dust the base and sides with half the icing sugar. Pour 100ml of the water into the bowl of your electric mixer and sprinkle over the gelatine.
- Pour the rest of the water and the sugar into a medium, heavy-based saucepan, place on medium-high heat, stirring all the time and bring to the boil.
- Put the lid on for 1 minute so the condensation washes down the side of the saucepan, getting rid of any sugar crystals that may have formed.
- Boil for 15 to 20 minutes with the lid off and with a sugar thermometer clipped to the side of the saucepan until it reads 115 degrees C (soft ball stage).
- As soon as the syrup is ready, start whisking the gelatine with your electric mixer using the flat beater on the lowest speed and then carefully pour in the syrup in a slow steady stream with the mixer running.
- When all the syrup is in, gradually increase the speed to high. Beat for about 20 minutes until it is snow white and very thick. Beat in the vanilla.
- Pour into the tin, scraping as much out of the bowl as possible. Spread it out. Dust the rest of the icing sugar over the marshmallow. Cover with cling film and leave to set for about 2 hours. Do not refrigerate or freeze.
- Cut into squares and dip the cut sides in the extra icing sugar. Keeps in an airtight container for 1 week.
To clean your mixing bowl, fill it with boiling water and leave to sit for 30 minutes and wipe it clean. For the saucepan where the syrup was, do the same thing or fill it with cold water and bring it up to the boil on the hob.
For Christmas marshmallows
If you want, you could substitute the vanilla with 1 1/2 teaspoons peppermint extract and add some green food colouring for a Christmassy effect.