Chill a coupe or Nick & Nora glass by placing it in the freezer for a few minutes or fill with ice water to chill. Once chilled, discard ice/water and quickly rinse the inside of the glass with the absinthe (about 0.1 oz) — swirl to coat and discard excess. Set the glass aside.

Dry shake (if using egg white)

If you are using the egg white for a silky texture, combine the vodka (2 oz), blue curaçao (0.5 oz), elderflower liqueur (0.5 oz), fresh lime juice (0.75 oz), simple syrup (0.25 oz), and egg white (0.5 oz) in a cocktail shaker without ice. Dry-shake vigorously for 15 seconds to emulsify and create foam.

Wet shake

Add ice (about 6 cubes) to the shaker. Shake vigorously for 12–18 seconds until the shaker chills and becomes very cold (this both chills and dilutes to balance the cocktail).

Strain and finish

Double-strain the cocktail into the prepared chilled glass using a Hawthorne strainer and a fine-mesh strainer to remove ice shards and any egg white solids. If you skipped egg white, simply shake all liquid ingredients with ice and strain.

Add shimmer (optional)

If using edible shimmer, add 1/2–1 tsp to the drink and stir gently once to create a shimmering photon-like effect across the surface.

Garnish and serve

Express a lime twist over the surface to release citrus oils, run it around the rim, and drop it into the drink, or float an edible flower. Serve immediately.