Prepare your pan by spraying the inside liberally with vegetable oil spray. I use an 8 inch (20 cm) square cake pan
Soak the gelatine leaves in enough cold water to cover the leaves. Let it sit for 5 minutes.
After 5 minutes, squeeze out the gelatine leaves and place them in a small mixing bowl of your stand mixer. Attach the whisk attachment and add the 80g of water to the gelatine leaves. Whisk on medium.
While the gelatine is whisking, place the 60g of water in a small saucepan, along with the caster sugar. Over low heat, bring the mixture to a boil, making sure all of the sugar has dissolved.
Turn the mixer to low and gradually add the sugar syrup down the side of the bowl to avoid splashes.
Add the vanilla and sea salt. Turn the mixer to high and whisk for another 10 minutes. Marshmallow will be thick and will set quickly, so you need to work quickly now
Pour the marshmallow into your prepared pan and smooth, then dust with combined cornflour and icing sugar. The leftover cornflour and sugar will be used after cutting the marshmallow
Cover the marshmallow with plastic wrap and store at room temperature overnight
Gently remove the marshmallow from the pan, then cut into squares with a large, sharp knife. Spraying the knife with cooking oil can stop it from sticking
Toss the cut marshmallows in leftover icing sugar and cornflour mixture
Store marshmallows in a sealed container or bag for gifting, coating it liberally with the cornflour and icing sugar. They should last up to 2 weeks
