Add the lychees and the lemon juice to a cocktail shaker. Muddle until the lychees break down and release all of their juice.

Pour the raspberry syrup into a glass, then fill the glass with ice.

Add the lychee mixture and the elderflower liqueur. Top with the Prosecco and lychee sparkling water, then gently stir to combine.

Garnish with fresh raspberries, a lychee, or a lemon slice, if desired. Enjoy!