Break one whole egg into a large mixing bowl. Separate the remaining whole egg, pouring the egg white into another clean bowl and the yolk into the mixing bowl, together with the third egg yolk and the sugar. Whisk the egg yolk mixture until it is pale and frothy, using an electric hand mixer.
Place the mixing bowl over a pan of simmering water and continue to whisk for about 10 minutes, adding the wine a little at a time, until the mixture has tripled in volume and is warm to the touch. Do not allow the water in the saucepan to boil while you are whisking. Remove the bowl from the heat.
Sprinkle the gelatine into 3 tbsp hot (not boiling) water in a jug, stir briskly until thoroughly mixed. If it does not fully dissolve because the liquid has cooled, stand the jug in a pan of hot water and continue to stir until fully dissolved. Do not allow the gelatine mixture to boil.
Pour the dissolved gelatine into the egg mixture and whisk in. Sit the bowl over a pan of cold water and continue whisking for a further 5 minutes until the zabaglione mixture is cold.
Whip the cream until lightly thickened and doubled in volume, then fold into the egg mixture. Whisk the egg white into stiff peaks, then also fold into the mixture. Spoon into six dessert glasses and chill in the fridge for at least 2 hours.
Just before serving, scatter the strawberries and raspberries evenly over the top of the desserts and decorate with sprigs of mint.