Chill champagne flutes or tall glasses in the fridge for about 10 minutes.
Fill a cocktail shaker with ice. Add vanilla vodka and simple syrup (if using).
Shake gently for 5–10 seconds to chill, then strain into the chilled glass, filling it about halfway.
Use tongs to gently place the cotton candy on top of the glass (do not submerge yet).
When ready to serve, slowly pour the sparkling wine over the cotton candy so it melts into the drink. Give a light stir with a bar spoon.
Garnish with fresh berries or a mint sprig and serve immediately.
Notes
Add the cotton candy right before pouring so it stays fluffy. Skip the simple syrup for a drier sip; the candy adds plenty of sweetness. For a zero-proof version, swap vodka and sparkling wine with lemon-lime soda or sparkling water.