Lightly grease a 20cm x 20cm tin lined with non-stick baking paper. Place the slightly warmed prosecco in the bowl of an electric mixer, sprinkle over the gelatine and stir to combine everything. Set aside over a bowl of warmed water. Place the sugar, glucose and prosecco in a medium saucepan over a medium heat and, warm up, stirring constantly until the sugar is dissolved. Add the orange peel and increase the heat to bring to the boil. Add a thermometer and cook, without stirring until the temperature reaches 115°C.
With the mixer running, gradually add the hot syrup in a thin, steady stream to the sponged gelatine mixture and beat for 5–7 minutes or until thick and glossy and the mixer bowl is cool enough to keep your hands on.
Carefully spoon the mixture into the tin and using a piece of greased baking paper, carefully smooth the marshmallow into an even layer. Refrigerate for 1–2 hours or until set.
To make the Aperol sherbet sugar, place the sugar, orange food colouring, Aperol, sherbet and orange zest in a bowl and mix to combine. Let the sugar dry out for 4 hours, or overnight on a tray until ready to use.
To decorate, turn the marshmallow out onto a surface and cut into roughly 2cm squares. Dust a piece of baking paper with the sherbet sugar and carefully roll the marshmallow squares in the mixture.