Grease a 20 x 20cm square tin with a flavourless oil (like vegetable oil) and line with baking parchment.

Mix the corn flour and icing sugar together in a small bowl. Using a sieve, dust the parchment-lined tin with an even layer of the icing sugar and corn flour mixture.

Place the gelatin in a bowl of cold water and leave it to soften. Remove the gelatin from the water and squeeze out any excess.

Place the gelatin in a small metal bowl set over a pot of simmering water and melt it, do not let the gelatine simmer. Keep it warm until you are ready to use it.

Melt the white chocolate, either using a bain-marie or in the microwave on short bursts - be careful white chocolate can burn very easily. Keep the chocolate warm, so that it stays runny.

Place the egg whites in the bowl of a stand mixer with the whisk attachment fitted.

Mix the granulated sugar, liquid glucose, and water in a large saucepan and bring to a simmer over a medium heat. Stir to dissolve the sugar, then simmer for about 5 minutes, until the syrup reaches 121C.

Let the syrup continue to cook and turn the mixer to medium speed, whisk the eggs until they are at soft peak stage.

Continue to boil the syrup and when it reaches 138-140 C remove it from the heat. Turn the mixer to medium speed and slowly pour the syrup into the egg whites.

Pour in the gelatin, increase the speed to medium-high, and mix for about 5 minutes, until the mixture is thickened, glossy, and warm but not hot.

Add the freeze-dried strawberry powder and whip for 30 seconds to mix it evenly. Gently fold in the melted chocolate with a spoon and make sure it's evenly mixed.

Spread the marshmallow into the prepared pan. Rub a small offset spatula with oil and use that to smooth the surface of the marshmallow.

To get an even and flat surface, cut a 20 x 20cm square of parchment and rub one side with the oil. Place the oiled side down on the surface of the marshmallow and gently press down.

Leave the marshmallows to set at room temperature overnight.

When set, remove the square of parchment paper and lift out the marshmallow using the parchment.

Rub a sharp knife with vegetable oil, trim the edges of the marshmallow and then cut them to your desired sizes/shapes 2-3cm squares are most common.

Dust the marshmallows with the icing sugar corn flour mix to prevent them from sticking together. Store in an airtight container at room temperature.