Fill a cocktail shaker halfway with ice. Add absinthe, elderflower liqueur, fresh lemon juice, and simple syrup.
Shake about 10 seconds until the shaker is cold.
Strain into the chilled glass. Fine‑strain for a silkier texture, if desired.
Top gently with chilled sparkling wine and garnish with a lemon twist or edible flower. Serve immediately.
Notes
Adjust sweetness by tweaking the simple syrup. Use very cold sparkling wine to keep the drink crisp. A touch more absinthe intensifies the herbal notes, but too much can overpower the balance.