Combine gin, egg white, orange flower water, lemon juice, lime juice and simple syrup in a cocktail shaker. Shake for 2 to 5 minutes until very frothy.
Add a small handful of small ice cubes/crushed ice and shake for 30 to 60 seconds or until the ice has melted (you no longer hear it).
Add cream and shake for a few seconds more.
Pour into a Collins (tall) glass and mix in soda water. The drink should be thick enough that a straw stands up in the center.
Notes
SIMPLE SYRUP 1 cup (8 ounces) water 1 cup granulated sugar Bring the water to a simmer in a saucepan set over medium-high heat. Add the sugar and stir until it completely dissolves. Remove the pan from the heat. Set aside to cool to room temperature. Pour the syrup into a clean 1-pint bottle, cap it and refrigerate it until needed. Makes 1½ cups and keeps two months or longer in the refrigerator.