Chill a coupe or martini glass in the freezer or with ice and water. If using fresh raspberries for garnish, rinse and pat dry. If using egg white, separate one egg and reserve the white.

Dry shake (if using egg white)

Add gin, dry vermouth, raspberry liqueur, fresh lemon juice, simple syrup, egg white (if using), and Angostura bitters to a cocktail shaker. Do not add ice yet. Dry-shake vigorously for 15–20 seconds to emulsify and build foam.

Wet shake

Add a generous handful of ice to the shaker (about 1 cup). Shake vigorously for 12–15 seconds until the outside of the shaker is very cold and frost appears.

Strain

Double-strain the mixture into the chilled coupe or martini glass using a fine mesh strainer to remove ice shards and any raspberry seeds or foam lumps. If you prefer a slightly lighter drink, use a single fine strainer.

Sparkling finish (optional)

If using sparkling wine, gently top the cocktail with 2 oz (about a splash) of chilled Champagne or dry sparkling wine. Pour slowly down the side of the glass to preserve foam from the egg white.

Garnish and serve

Thread 2 fresh raspberries on a small cocktail pick or float them in the drink. Express a lemon twist over the surface to release essential oils, then drop the twist into the drink or rest on the rim. Serve immediately.