In a metal mixing bowl or cocktail shaker add the egg white and rose syrup and--using a mini frother--aerate until you have soft peaks; set aside. Add gin, Crème Yvette, and lemon juice to a cocktail shaker filled with ice; shake until cold; strain and pour into a coupe glass. Gently spoon the rose meringue on top of the cocktail and garnish with a cucumber slice on the rim of the glass.
This is a very botanical/floral cocktail, and although there are other violette liqueurs on the market the fruit balancing flavors of the Crème Yvette prevent the drink from being too perfume-ie. *the meringue takes ~ a minute to set up, so if you're doing multiple cocktails you may want to get it ready ahead of time. **whip the meringue at room temperature
A good friend of mine was looking to replicate--in drink form--a very interesting summer rose syrup custard we had had years ago. This drink combines those great floral notes and creaminess with a wonderful evenness of sweet and tart.