Remove the green from the strawberries and put the strawberries in the blender. Put a scoop of ice in the shaker and add the blended strawberries. Then pour 10 cl of Prosecco in the blender followed by 1cl of sugar syrup. If you prefer your Rossini not to be too sweet, then don't add the sugar syrup. Don't shake the mixture, because that would have a negative effect on the Prosecco. Just stir everything gently around. Pour the mixture through a strainer in a champagne flute or a wine glass. Enjoy your Rossini cocktail.