In a cocktail shaker, combine 2 oz. gin, 1 oz. St-Germain elderflower liqueur, 1 oz. green chartreuse, the juice of 1/2 lemon, 1/2 tsp. agave syrup, 2 to 3 dashes amargo bitters and 1 pasteurized egg white with ice. Shake well. Strain into an ice-filled collins glass. Top with club soda and garnish with a lemon wheel.