Add gin, fresh lemon juice, crème de cassis, simple syrup, orange bitters, and the egg white (if using) to a cocktail shaker. Seal and shake vigorously without ice for 12–15 seconds to emulsify the egg white and build a silky texture.

Wet shake

Open the shaker, add the cubed ice, reseal, and shake hard for 12–15 seconds until well chilled and the outside of the shaker is frosty.

Strain & serve

Discard the ice or water from the chilled glass. Double-strain the cocktail through a fine mesh strainer into the chilled coupe or Nick & Nora glass to remove ice shards and any coagulated egg white.

Garnish & Finish

Express the oils of a lemon twist over the surface of the cocktail, then run the peel around the rim and drop it into the drink or set it on the rim.

If desired, float a fresh blackberry or a brandied cherry on the surface for visual contrast and an extra hint of fruitiness.

Serve immediately. The cocktail should present as a pale, slightly rosy drink with a silky foam (if egg white was used) and a subtle cassis sweetness balanced by bright lemon and botanicals from the gin.