In a small bowl mix together the icing sugar and corn flour, use a fork to ensure they are thoroughly combined.
Line a baking tray with cling film, you can spray or rub some oil onto the tray to help it stick, then take around 30% of the icing sugar/corn flour mixture and dust the lined baking tray with it. Keep the remainder of the mixture to one side for later.
Put the sugar, tonic and glucose into a medium saucepan and gentley heat until the mixture reaches 121°C. .
Whilst the sugar mix is coming to temperature, soak your gelatine in the 100g gin.
Using a clean, degreased mixing bowl, start to beat the egg whites when the sugar gets to 110°C. You’re aiming to get the egg whites into stiff peaks at roughly the same time as your sugar mix gets to 121°C.
When the mix reaches temperature, slowly pour this into egg whites whilst continuing to mix on a medium speed. Once all of the sugar has been incorporated, add the gin soaked gelatine along with any gin not soaked up and continue to beat until the outside of the bowl is cool.
Once cool, scoop the marshmallow mixture into your prepared baking tray and use a palette knife in long, gentle swipes to ensure the mixture reaches all of the edges and is smooth and flat on the surface. It helps to have a jug of hot water to hand so you can dip the palette knife as it makes smoothing out the surface much easier.
Leave on the kitchen worktop for around an hour to set.
Once completely set, put some of the icing sugar/corn flour mix into a sieve and lightly dust the top of the marshmallow. Place a chopping board on top of the baking tray and then flip both the tray & board upside down to turn out the marshmallow. Remove the clingfilm and lighty dust the surface with the icing sugar/cornflour mix.
Stand a sharp knife in a jug of hot water for three minutes then wipe it dry and cut the marshmallows into your desired shape. Dip the knife back into the hot water after each cut and wipe it dry and clean before cutting again.
Once you have all of the marshmallows, dip them in the remaining sugar/corn flour mixture ensuring they are well coated. Your gin & tonic marshmallows are now ready to serve and enjoy.
